Eliminate silly warnings

	* src/ui/TTY/terminfo.c (emacs_tparam): We don't control tparm
	prototype where some have const qualifiers others don't. Turning
	the warning off is the sensible choice.

	* src/ui/glyphs-eimage.c (gif_instantiate): Small cosmetic change.

	* src/ui/X11/event-Xt.c (init_event_Xt_late): We don't control the
	prototype for XtAppSetTypeConverter where some have const others don't
	so turning the warning off is the sensible option...

	* src/ui/X11/device-x.c (Fx_get_font_path): Const all around keeps
	compilers happy.

	* src/events/event-stream.c (asyneq_handle_non_command_event): Use
	a void* temporary to sidestep warning.

	* src/regex.c (POP_FAILURE_POINT): Don't cast unnecessarily.
	(re_match_2_internal): Turn off const cast warning since the code
	will always need it one macro expansion or another. Can't win here
	without cheating :)

	* src/buffer.c (directory_is_current_directory): Cast
	to target type, when conversion fails.

Signed-off-by: Nelson Ferreira <nelson.ferreira@ieee.org>