If available, use Xfixes extension to do pointer blanking.

If available, use Xfixes extension to do pointer blanking.

* configure.ac (HAVE_XFIXES): Define if available.
(XFIXES_CFLAGS, XFIXES_LIBS): New AC_SUBSTs.
* src/Makefile.in (XFIXES_CFLAGS, XFIXES_LIBS): New var.
* src/xfns.c (x_set_mouse_color): Do not call make_invisible_cursor here.
(make_invisible_cursor): Move to...
* src/xterm.c (make_invisible_cursor): ...here.
(x_probe_xfixes_extension, xfixes_toggle_visible_pointer)
(x_toggle_visible_pointer, x_setup_pointer_blanking): New functions.
(x_term_init): Call to x_setup_pointer_blanking.
(XTtoggle_invisible_pointer): Use blanking specific to this display.
* src/xterm.h (struct x_display_info): New member toggle_visible_pointer.