Now that upstream provides a stable/versioned API, it will be
easier to deal with than with submodules.

configure.ac tries to assign a default value of 0 to the micro version if it's
empty, but the shell variable assignemnt doesn't work because there's whitespace
around the '=' sign.

This results in SPICE_GTK_MICRO_VERSION being defined to (), which causes a
compilation failure in files that include it.

A client setting this capability indicates to the server that it's able
to handle SASL authentication, and it also indicates that if SASL is
to be used for authentication, then it won't expect a valid 'pub_key' field
in SpiceLinkReply.

The reason for making guarantees about not looking at the pub_key field is
that its presence and size is hardcoded in the protocol, but in some
hardened setups (using fips mode), generating a RSA 1024 bit key as
expected is forbidden and fails. With this new capability, the server
knows the client will be able to handle SASL if needed, and can skip
the generation of the key altogether. This means that on the setups
described above, SASL authentication has to be used.

Address Alon's review from
http://lists.freedesktop.org/archives/spice-devel/2014-March/016383.html

Allow to specify the shared directory from the command line, or at
runtime via properties. (still default to xdg public share, if none
specified)

See spice-common for protocol details.  phodav, a webdav server library,
is imported thanks to a submodule, until this project has a stable API
and releases.

The webdav channel is reponsible for handling port events and
multiplexing the request streams. Extra care has been made to avoid
blocking and to enable some fairness between concurrent streams, however
this has been particularly tricky and is likely to have some issues
left.

The webdav server is run in a seperate thread, using libsoup. The client
communication is done via a local tcp socket, but protected to only
accept local connection and with a pretty strong password.

The home directory is exported for the remote to browse, which seems to
be a sensible default atm.

When building with mingw64, several warnings about using the wrong format
specifier for gssize/gsize occur similar to:

win-usb-dev.c: In function 'g_udev_client_list_devices':
win-usb-dev.c:145:21: error: format '%i' expects argument of type 'int', but argument 7 has type 'gssize' [-Werror=format=]
                     name, errstr, rc);

This commit makes use of the G_GSIZE_FORMAT/G_GSSIZE_FORMAT macros provided
by glib to silence these warnings.

I've checked that this does not introduce new warnings on linux and mingw32
builds.

Fix screenshot of secondary displays, with an area position != (0,0).

This has never been working correctly since the surface display "area"
was introducted in:

commit e3bb7b1c
Author: Marc-André Lureau <marcandre.lureau@redhat.com>
Date:   Tue Jun 12 19:24:47 2012 +0200

    display: learn to restrict display to an area

https://bugzilla.redhat.com/show_bug.cgi?id=1029761

cc1: warnings being treated as errors
spice-uri.c: In function ‘spice_uri_parse’:
spice-uri.c:105: error: ‘saveptr’ may be used uninitialized in this
function [-Wuninitialized]
spice-uri.c:105: error: ‘saveptr2’ may be used uninitialized in this
function [-Wuninitialized]

While looking at the SASL code, I noticed some memory leaks in error paths.
This commit adds a cleanup: block to free some of the memory dynamically
allocated in that function, and remove the corresponding g_free() from
the regular code flow. This should ensure that both the regular path
and the error paths free the same memory.

This fixes at least this 'mechlist' leak which I got during regular SASL
PLAIN authentication:
==3452== 6 bytes in 1 blocks are definitely lost in loss record 140 of 11,706
==3452==    at 0x4A0645D: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.s
==3452==    by 0x35BAC4EE6E: g_malloc (gmem.c:104)
==3452==    by 0x5BF7CAA: spice_channel_perform_auth_sasl (spice-channel.c:1440)
==3452==    by 0x5BF9033: spice_channel_recv_link_msg (spice-channel.c:1727)
==3452==    by 0x5BFAECD: spice_channel_coroutine (spice-channel.c:2348)
==3452==    by 0x5C35D6D: coroutine_trampoline (coroutine_ucontext.c:63)
==3452==    by 0x5C35A1B: continuation_trampoline (continuation.c:51)
==3452==    by 0x31342479BF: ??? (in /usr/lib64/libc-2.18.so)
==3452==    by 0x75F2940591224CFF: ???
==3452==    by 0xE756E5F: ???
==3452==    by 0xE7589BF: ???
==3452==    by 0xFFEFFF78F: ???
==3452==    by 0x5BFCD92: g_io_wait_helper (gio-coroutine.c:43)
=

This is recommended by autoconf documentation
http://nondot.org/sabre/Mirrored/autoconf-2.12/autoconf_3.html#SEC15
and some #defines in config.h can change what happens in system headers,
so config.h has to be included first.

The only file which does not get this treatment is
gtk/spice-client-gtk-module.c as this breaks the build on gtk+2:

CC       SpiceClientGtk_la-spice-client-gtk-module.lo
In file included from /usr/include/python2.7/pyconfig.h:6:0,
                 from /usr/include/python2.7/Python.h:8,
                 from /usr/include/pygtk-2.0/pygobject.h:5,
                 from spice-client-gtk-module.c:20:
/usr/include/python2.7/pyconfig-64.h:1182:0: error: "_POSIX_C_SOURCE" redefined [-Werror]
 #define _POSIX_C_SOURCE 200112L
 ^
In file included from /usr/include/limits.h:25:0,
                 from /usr/lib/gcc/x86_64-redhat-linux/4.8.2/include/limits.h:168,
                 from /usr/lib/gcc/x86_64-redhat-linux/4.8.2/include/syslimits.h:7,
                 from /usr/lib/gcc/x86_64-redhat-linux/4.8.2/include/limits.h:34,
                 from /usr/lib64/glib-2.0/include/glibconfig.h:11,
                 from /usr/include/glib-2.0/glib/gtypes.h:34,
                 from /usr/include/glib-2.0/glib/galloca.h:34,
                 from /usr/include/glib-2.0/glib.h:32,
                 from /usr/include/glib-2.0/gobject/gbinding.h:30,
                 from /usr/include/glib-2.0/glib-object.h:25,
                 from ./glib-compat.h:24,
                 from ../config.h:201,
                 from spice-client-gtk-module.c:18:
/usr/include/features.h:228:0: note: this is the location of the previous definition
 #  define _POSIX_C_SOURCE 200809L
 ^
cc1: all warnings being treated as errors

After e124a3b2 which added the SPICE_GTK_CHECK_VERSION macro, a non-fatal
'./configure: line 15251: x24: command not found' appears in configure
output. This is because [ ] is not interpreted as the 'test' command by
autoconf, but is rather used as a way to quote configure.ac content.
This commit replaces the use of [] with a more typical AS_IF.

wocky-http-proxy.c and vmcstream.c make use of functions that were
not available in glib 2.26 so we need fallback for them through
glib-compat.h or spice-gtk won't build with older glibs.

Since 1fcaaa15, display_surface is
allocated using gslice. However MSG_DISPLAY_MODE handler didn't allocate
using GSlice. This can eventually lead to a crash when freeing, such as:

Thread no. 1 (6 frames)
 #2 g_slice_free1 at gslice.c:1097
 #3 iter_remove_or_steal at ghash.c:787
 #4 clear_surfaces at /lib64/libspice-client-glib-2.0.so.8
 #5 spice_display_channel_finalize at
 /lib64/libspice-client-glib-2.0.so.8
 #7 spice_channel_delayed_unref at /lib64/libspice-client-glib-2.0.so.8
 #12 gtk_main at gtkmain.c:1158

https://bugzilla.redhat.com/show_bug.cgi?id=1069546

Learn to return the currently configured proxy, to allow
client to tweak parameters, such as username and password.

Add a function to retrieve the last GError from a channel, this may be
useful to provide additional error details to the client.

Generalize a little bit SpiceProxy to allow easy URI manipulation by
clients.

Get rid of a superflous g_socket_condition_check().

Although reusing BIO_new_socket() once again is a hack, it seems
to be the easiest way... The proper solution is certainly to start
using GTls instead, but that will require a glib 2.28 dep bump.

This way, the call might eventually support more proxy and
authentication.

This will require glib 2.28 for GTls support, atm

Or Squid will fail with:
WARNING: Unsupported or unconfigured/inactive proxy-auth scheme

We want just host:port here.

The following Spice proxy URI parsing code makes use of it, but it is
not available on Windows

Origin:
http://git.videolan.org/gitweb.cgi/vlc.git/?p=vlc.git;a=blob;f=compat/strtok_r.c

This allows to use conveniently GIOStream APIs without caring about
coroutine and Spice messages details.

Refactor port code to create a private GIO async function that can send
SPICE_MSGC_SPICEVMC_DATA message over any channel.