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: I89fda12d826783ffe18142ba048ff10bd769e240
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>

arch/arm64/Makefile

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index ab22981..f736cda 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -37,7 +37,14 @@
   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-asynchronous-unwind-tables
 KBUILD_CFLAGS	+= $(call cc-option, -mpc-relative-literal-loads)
 KBUILD_CFLAGS	+= -fno-pic