Strengthen compatibility warning for GCC builtins

This is necessary for vector builtins, which are picky about the
signedness of the element type.

gcc/ada/
	* libgnat/s-atopri.ads (bool): Delete.
	(Atomic_Test_And_Set): Replace bool with Boolean.
	(Atomic_Always_Lock_Free): Likewise.
	* libgnat/s-aoinar.adb (Is_Lock_Free): Adjust.
	* libgnat/s-aomoar.adb (Is_Lock_Free): Likewise.
	* libgnat/s-aotase.adb (Atomic_Test_And_Set): Likewise.
	* libgnat/s-atopex.adb (Atomic_Compare_And_Exchange): Likewise.
	* gcc-interface/decl.c: Include gimple-expr.h.
	(intrin_types_incompatible_p): Delete.
	(intrin_arglists_compatible_p): Call types_compatible_p.
	(intrin_return_compatible_p): Likewise.