Don't import llvm.mk for non-portable builds.

Change-Id: I447e7d816c0e4f84bc4d13bc34ff93b026d192b5
diff --git a/build/Android.common.mk b/build/Android.common.mk
index 188ddb5..a4f13b8 100644
--- a/build/Android.common.mk
+++ b/build/Android.common.mk
@@ -116,9 +116,11 @@
 ART_DEFAULT_GC_TYPE ?= CMS
 ART_DEFAULT_GC_TYPE_CFLAGS := -DART_DEFAULT_GC_TYPE_IS_$(ART_DEFAULT_GC_TYPE)
 
-LLVM_ROOT_PATH := external/llvm
-# Don't fail a dalvik minimal host build.
--include $(LLVM_ROOT_PATH)/llvm.mk
+ifeq ($(ART_USE_PORTABLE_COMPILER),true)
+  LLVM_ROOT_PATH := external/llvm
+  # Don't fail a dalvik minimal host build.
+  -include $(LLVM_ROOT_PATH)/llvm.mk
+endif
 
 # Clang build support.
 # Target builds use GCC by default.