x86/build: Don't add -maccumulate-outgoing-args w/o compiler support

Clang does not support this machine dependent option.

Older versions of GCC (pre 3.0) may not support this option, added in
2000, but it's unlikely they can still compile a working kernel.
Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170509032946.20444-1-nick.desaulniers@gmail.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/Makefile

@@ -179,7 +179,8 @@ ifdef CONFIG_JUMP_LABEL
 endif
 
 ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
-	KBUILD_CFLAGS += -maccumulate-outgoing-args
+	# This compiler flag is not supported by Clang:
+	KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
 endif
 
 # Stackpointer is addressed different for 32 bit and 64 bit x86