* dbus/dbus-auth.c (record_mechanisms): memleak fixes

	* dbus/dbus-sysdeps.c (_dbus_string_save_to_file): fix some
	memleaks

	* dbus/dbus-keyring.c (add_new_key): fix a memleak, and
	on realloc be sure to update the pointer in the keyring

	* dbus/dbus-string.c (_dbus_string_zero): compensate for align
	offset to avoid writing to unallocated memory

	* dbus/dbus-auth.c (process_rejected): return FALSE if we fail to
	try the next mechanism, so we properly handle OOM

	* dbus/dbus-keyring.c (_dbus_keyring_new_homedir): fix double-free
	on OOM.
	(_dbus_keyring_new): fix OOM bug
	(_dbus_keyring_new_homedir): always set error; impose a maximum
	number of keys we'll load from the file, mostly to speed up the
	test suite and make its OOM checks more useful, but also for
	general sanity.

	* dbus/dbus-auth.c (process_error_server): reject authentication
	if we get an error from the client
	(process_cancel): on cancel, send REJECTED, per the spec
	(process_error_client): send CANCEL if we get an error from the
	server.