ext/gio/gstgio.c: Remove nowadays unnecessary workaround for a crash.

ext/gio/gstgio.c: Remove nowadays unnecessary workaround for a crash.

Original commit message from CVS:
* ext/gio/gstgio.c: (plugin_init):
Remove nowadays unnecessary workaround for a crash.
* ext/gio/gstgiosink.c: (gst_gio_sink_finalize),
(gst_gio_sink_start), (gst_gio_sink_stop),
(gst_gio_sink_unlock_stop):
* ext/gio/gstgiosink.h:
* ext/gio/gstgiosrc.c: (gst_gio_src_finalize), (gst_gio_src_start),
(gst_gio_src_stop), (gst_gio_src_unlock_stop):
* ext/gio/gstgiosrc.h:
Make the finalize function safer, clean up everything that could stay
around.
Reset the cancellable instead of creating a new one after cancelling
some operation.
Don't store the GFile in the element, it's only necessary for creating
the streams.