* xterm.h (struct x_output): For 'black_relief' and 'white_relief'

* xterm.h (struct x_output): For 'black_relief' and 'white_relief'
fields, drop 'allocated_p' member and use -1 for uninitialized value.
* w32term.h (struct w32_output): Similarly but do not use -1 because...
* xfaces.c (unload_color) [HAVE_X_WINDOWS]: ...this function is a no-op
on MS-Windows anyway.
(free_face_colors): Define only if HAVE_X_WINDOWS and...
(free_realized_face): ...adjust user.
* xfns.c (Fx_create_frame, x_create_tip_frame): Initialize black and
white relief pixels to -1.
* xterm.c (x_setup_relief_color, x_free_frame_resources): Adjust users.
* w32term.c (w32_setup_relief_color, x_free_frame_resources): Likewise.
* dispextern.h (unload_color): Move prototype under HAVE_X_WINDOWS.