Minor fix to be consistent with the style today.

Change-Id: Ic3967570d71440801635fd83a90b7dfddea667be
diff --git a/build/Android.common.mk b/build/Android.common.mk
index 81cfe51..dd92042 100644
--- a/build/Android.common.mk
+++ b/build/Android.common.mk
@@ -71,9 +71,7 @@
 	-fstrict-aliasing
 
 ifeq ($(ART_USE_LLVM_COMPILER),true)
-art_cflags := \
-	$(art_cflags) \
-	-DART_USE_LLVM_COMPILER=1
+art_cflags += -DART_USE_LLVM_COMPILER=1
 endif
 
 ifeq ($(HOST_OS),linux)