Add libclang for target.

Change-Id: I3dc5de6c1a4e7f5ba64196dd8ee0965ef10d4e8b
diff --git a/clang.mk b/clang.mk
index 587a510..9165578 100644
--- a/clang.mk
+++ b/clang.mk
@@ -3,5 +3,6 @@
 endif
 
 CLANG_HOST_BUILD_MK := $(CLANG_ROOT_PATH)/clang-host-build.mk
+CLANG_DEVICE_BUILD_MK := $(CLANG_ROOT_PATH)/clang-device-build.mk
 CLANG_TBLGEN_RULES_MK := $(CLANG_ROOT_PATH)/clang-tblgen-rules.mk
 CLANG_VERSION_INC_MK := $(CLANG_ROOT_PATH)/clang-version-inc.mk