Do not use clang for mips target.

Clang assembler cannot compile some inlined assembly code
in valgrind_malloc_space-inl.h:192:5: error: used $at without ".set noat"
However, clang generated assembly code for runtime/mirror/array.cc
cannot be compiled by gas.

BUG: 18789639
BUG: 18807290
Change-Id: Ifdeb3c50f11cefc7f0d62c1d36fdd1f8b9344fb4
diff --git a/sigchainlib/Android.mk b/sigchainlib/Android.mk
index b7ff360..35dec4b 100644
--- a/sigchainlib/Android.mk
+++ b/sigchainlib/Android.mk
@@ -28,6 +28,7 @@
 LOCAL_SHARED_LIBRARIES := liblog
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_ADDITIONAL_DEPENDENCIES += art/build/Android.common_build.mk
+$(eval $(call set-target-local-clang-vars))
 include $(BUILD_SHARED_LIBRARY)
 
 include $(CLEAR_VARS)
@@ -40,6 +41,7 @@
 LOCAL_SHARED_LIBRARIES := liblog
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_ADDITIONAL_DEPENDENCIES += art/build/Android.common_build.mk
+$(eval $(call set-target-local-clang-vars))
 include $(BUILD_STATIC_LIBRARY)
 
 # Build host library.