ANDROID: HACK: arm64: use -mno-implicit-float instead of -mgeneral-regs-only

LLVM bug 30792 causes clang's AArch64 backend to crash compiling
arch/arm64/crypto/aes-ce-cipher.c.  Replacing -mgeneral-regs-only with
-mno-implicit-float is the suggested workaround.

Drop this patch once the clang bug has been fixed.

Change-Id: I7c7bb9315a281970698120a6d2a9fcd126aad65e
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>

Author: greghackmann

arch/arm64/Makefile

@@ -30,7 +30,14 @@ $(warning LSE atomics not supported by binutils)
   endif
 endif
 
-KBUILD_CFLAGS	+= -mgeneral-regs-only $(lseinstr)
+ifeq ($(cc-name),clang)
+# This is a workaround for https://bugs.llvm.org/show_bug.cgi?id=30792.
+# TODO: revert when this is fixed in LLVM.
+KBUILD_CFLAGS	+= -mno-implicit-float
+else
+KBUILD_CFLAGS	+= -mgeneral-regs-only
+endif
+KBUILD_CFLAGS	+= $(lseinstr)
 KBUILD_CFLAGS	+= -fno-pic
 KBUILD_CFLAGS	+= $(call cc-option, -mpc-relative-literal-loads)
 KBUILD_CFLAGS	+= -fno-asynchronous-unwind-tables