x86/kbuild: Use cc-option to enable -falign-{jumps/loops}

clang currently does not support these optimizations, only enable them
when they are available.
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michael Davidson <md@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: grundler@chromium.org
Link: http://lkml.kernel.org/r/20170413172609.118122-1-mka@chromium.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/Makefile

@@ -88,10 +88,10 @@ else
         KBUILD_CFLAGS += -m64
 
         # Align jump targets to 1 byte, not the default 16 bytes:
-        KBUILD_CFLAGS += -falign-jumps=1
+        KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
 
         # Pack loops tightly as well:
-        KBUILD_CFLAGS += -falign-loops=1
+        KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
 
         # Don't autogenerate traditional x87 instructions
         KBUILD_CFLAGS += $(call cc-option,-mno-80387)