gst/gstthread.c: Ref the thread object in the GThread mainloop. Break out of the...

gst/gstthread.c: Ref the thread object in the GThread mainloop. Break out of the thread mainloop if it holds the last...

Original commit message from CVS:
* gst/gstthread.c: (gst_thread_dispose), (gst_thread_change_state),
(gst_thread_child_state_change), (gst_thread_main_loop):
Ref the thread object in the GThread mainloop. Break out of the
thread mainloop if it holds the last ref. This properly exits
the threads when disposing the thread from its own context. It
also avoids possible deadlocks in the dispose function.