Fix X GC leak in GTK and raw (no toolkit) X ports.

Fix X GC leak in GTK and raw (no toolkit) X ports.
* xterm.c (x_free_frame_resources): If white and black relief
GCs are allocated, always free them here.
* xfns.c (x_make_gc): Omit redundant initialization.
* widget.c (create_frame_gcs): Remove the leftover.
(EmacsFrameDestroy): Do nothing because all GCs are now freed
in x_free_frame_resources.