targhooks.c (default_libcall_value): Don't use LIBCALL_VALUE macro if not defined.

	* targhooks.c (default_libcall_value): Don't use LIBCALL_VALUE macro
	if not defined. Change type of second argument to const_rtx.
	(default_function_value): Call gcc_unreachable if FUNCTION_VALUE
	macro not defined.
	* targhooks.h (default_libcall_value): Update prototype.
	* target.h (struct gcc_target): Change type of second argument of
	libcall_value to const_rtx.
	* config/arm/arm.c (arm_libcall_value): Change type of second argument
	to const_rtx.
	(arm_libcall_uses_aapcs_base): Change type of argument to const_rtx.
	* doc/tm.texi (TARGET_LIBCALL_VALUE):  Revise documentation.

From-SVN: r152933