When we quickly switch from PLAYING to PAUSED and back to PLAYING it's possible
in some cases that the task refuses to start, This is because when we go to
PAUSED, we unschedule the clock timeout, which could return UNSCHEDULED when
we're back to PLAYING, causing the task to PAUSE again with a wrong-state.

This patch checks if we are running when we return with an UNSCHEDULED return
value and if we are, try to create a new buffer.

Fixes #597550

From 6380d4b to 85d1530

Fixes bug #598297.

This is slightly more efficient because the compiler can't do tail
recursion here and has to keep all stack frames.

Not that efficiency is that important here but I already had
the iterative version somewhere else and both are easy to read.

Fixes a compiler warning from the function being compiled but not
used.

Make the GST_POLL debug category symbol private to libgstreamer, as
there should be no external users of it.

This test used to SIGBUS on OS/X but now SIGSEGV's instead on
Snow Leopard. It's not worth the effort to figure out which platform
should produce which error for what is fundamentally a pretty silly
test, so just disable it on OS/X

This allows the macosx versions to properly error out when fds are closed.

This is only a temporary fix until the pluginloader is switched to not
use GstPoll but GIOChannels.

This is needed so that select properly errors out on macosx (sigh)

This is needed to properly detect fds that are closed or that got
an error

In the plugin loader subprocess, move stdin and stdout to new fd's
so that plugins printing things during plugin init or (*gasp*)
possibly reading from stdin don't interfere with the data sent to
and from the parent.

From 37f898b to a3e3ce4

When the plugin-scanner load fails (because the helper can't be
spawned), make sure to load the plugin that failed in-process, so
that all plugins do get loaded.

Add the GST_PLUGIN_SCANNER env var to the check environment here too
so that it doesn't fail when no installed scanner is available.

Split gst_queue_locked_enqueue() into variant for buffer and event to get rid of
the if() and make the code more readable (constant boolean parameters are never
nice). Removes the if (item) checks as we dereference the pointer before anyway.

Also apply the same idea of reusing the previous knowledge in
gst_queue_locked_dequeue to remove more type checks.

Split gst_multi_queue_item_new into buffer and event variant to make save an if
and make code more readable.