ART: Only give Clang warning when Clang is active

Do not pollute output with Clang warning if we were supposed to
compile with Clang.

Change-Id: I1ee764dcfe0581e09a350cb01fdf0ba06dd18b56
diff --git a/build/Android.common_build.mk b/build/Android.common_build.mk
index 1e07430..086f298 100644
--- a/build/Android.common_build.mk
+++ b/build/Android.common_build.mk
@@ -84,7 +84,7 @@
 ART_TARGET_CLANG := false
 endif
 
-ifeq ($(TARGET_ARCH),mips)
+ifeq ($(TARGET_ARCH)|$(ART_TARGET_CLANG),mips|true)
   # b/18807290, Clang generated mips assembly code for array.cc
   # cannot be compiled by gas.
   # b/18789639, Clang assembler cannot compile inlined assembly code in