* Makefile.in: Undef LIB_STANDARD before defining it to silence warning

* Makefile.in: Undef LIB_STANDARD before defining it to silence warning
in case it was defined already.
USE @GNUSTEP_MAKEFILES@ rather than envvars.
* nsterm.m (ns_term_init): Pass Qt and Qnil rather than YES/NO to
ns_default.
(applicationShouldTerminate, setValuesFromPanel): Use EQ to compare
Lisp_Objects.
* nsterm.h (Fx_display_grayscale_p, Fx_display_planes)
(ns_defined_color, ns_color_to_lisp): Declare.
* nsselect.m (ns_handle_selection_request, ns_handle_selection_clear)
(Fns_own_selection_internal): Make the big ugly hack more explicit, so
it's accepted even with USE_LISP_UNION_TYPE.
* nsmenu.m (ns_update_menubar): Use EQ to compare Lisp_Objects.
(update_frame_tool_bar): Remove apparently obsolete tests for
non-integerness of f->tool_bar_lines.
(windowShouldClose, addButton, clicked, runDialogAt): Make the big ugly
hack more explicit, so it's accepted even with USE_LISP_UNION_TYPE.
* nsfont.m (nsfont_driver): Use just 0 rather than an invalid cast.
(nsfont_open): Don't confuse NULL for Qnil.
* nsfns.m (ns_implicitly_set_icon_type): Use EQ to compare Lisp_Objects.
* menu.h (find_and_call_menu_selection):
* menu.c (find_and_call_menu_selection): Use just int for vector size.
(find_and_return_menu_selection): Always return something.
* frame.h: Include dispextern.h for Display_Info.
(display_x_get_resource): Declare.
* configure.in: Extract and substitute GNUSTEP_MAKEFILES.