Fix the GNUstep build

* src/Makefile.in (NON_OBJC_CFLAGS): Add
-Wflex-array-member-not-at-end.

* src/lisp.h (flush_stack_call_func): "asm" is unavailable in
Objective C.

* src/nsfns.m (ns_make_frame_key_window): Delete unused
function.

src/Makefile.in

@@ -423,7 +423,7 @@ endif
 
 # Flags that might be in WARN_CFLAGS but are not valid for Objective C.
 NON_OBJC_CFLAGS = -Wignored-attributes -Wignored-qualifiers -Wopenmp-simd \
-  -Wnested-externs -Wstrict-flex-arrays
+  -Wnested-externs -Wstrict-flex-arrays -Wflex-array-member-not-at-end
 # Ditto, but for C++.
 NON_CXX_CFLAGS = -Wmissing-prototypes -Wnested-externs -Wold-style-definition \
   -Wstrict-prototypes -Wno-override-init

src/lisp.h

@@ -4508,7 +4508,7 @@ flush_stack_call_func (void (*func) (void *arg), void *arg)
   /* Work around GCC sibling call optimization making
      '__builtin_unwind_init' ineffective (bug#65727).
      See <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115132>.  */
-#if defined __GNUC__ && !defined __clang__
+#if defined __GNUC__ && !defined __clang__ && !defined __OBJC__
   asm ("");
 #endif
 }

src/nsfns.m

@@ -690,12 +690,6 @@ Turn the input menu (an NSMenu) into a lisp list for tracking on lisp side.
   SET_FRAME_GARBAGED (f);
 }
 
-void
-ns_make_frame_key_window (struct frame *f)
-{
-  [[FRAME_NS_VIEW (f) window] makeKeyWindow];
-}
-
 /* tabbar support */
 static void
 ns_set_tab_bar_lines (struct frame *f, Lisp_Object value, Lisp_Object oldval)