Switch to LLVM 3.4 prebuilts in AOSP.

Change-Id: I064e953fb1bf69e7e321616647aab88dcc39af76
diff --git a/core/clang/config.mk b/core/clang/config.mk
index d134a8d..1fd69d7 100644
--- a/core/clang/config.mk
+++ b/core/clang/config.mk
@@ -1,8 +1,18 @@
+ifeq (true,$(FORCE_BUILD_LLVM_COMPONENTS))
+LLVM_PREBUILTS_PATH := $(BUILD_OUT_EXECUTABLES)
+LLVM_PREBUILTS_HEADER_PATH := external/clang/lib/include
+else
+LLVM_PREBUILTS_PATH := prebuilts/clang/$(BUILD_OS)-x86/host/3.4/bin
+LLVM_PREBUILTS_HEADER_PATH := prebuilts/clang/$(BUILD_OS)-x86/host/3.4/lib/clang/3.4/include/
+endif
 
-CLANG := $(HOST_OUT_EXECUTABLES)/clang$(HOST_EXECUTABLE_SUFFIX)
-CLANG_CXX := $(HOST_OUT_EXECUTABLES)/clang++$(HOST_EXECUTABLE_SUFFIX)
-LLVM_AS := $(HOST_OUT_EXECUTABLES)/llvm-as$(HOST_EXECUTABLE_SUFFIX)
-LLVM_LINK := $(HOST_OUT_EXECUTABLES)/llvm-link$(HOST_EXECUTABLE_SUFFIX)
+CLANG := $(LLVM_PREBUILTS_PATH)/clang$(BUILD_EXECUTABLE_SUFFIX)
+CLANG_CXX := $(LLVM_PREBUILTS_PATH)/clang++$(BUILD_EXECUTABLE_SUFFIX)
+CLANG_TBLGEN := $(LLVM_PREBUILTS_PATH)/clang-tblgen$(BUILD_EXECUTABLE_SUFFIX)
+LLVM_AS := $(LLVM_PREBUILTS_PATH)/llvm-as$(BUILD_EXECUTABLE_SUFFIX)
+LLVM_LINK := $(LLVM_PREBUILTS_PATH)/llvm-link$(BUILD_EXECUTABLE_SUFFIX)
+TBLGEN := $(LLVM_PREBUILTS_PATH)/tblgen$(BUILD_EXECUTABLE_SUFFIX)
+
 
 # Clang flags for all host or target rules
 CLANG_CONFIG_EXTRA_ASFLAGS :=
@@ -46,8 +56,8 @@
 
 
 # Clang compiler-specific libc headers
-CLANG_CONFIG_EXTRA_HOST_C_INCLUDES := external/clang/lib/include
-CLANG_CONFIG_EXTRA_TARGET_C_INCLUDES := external/clang/lib/include $(TARGET_OUT_HEADERS)/clang
+CLANG_CONFIG_EXTRA_HOST_C_INCLUDES := $(LLVM_PREBUILTS_HEADER_PATH)
+CLANG_CONFIG_EXTRA_TARGET_C_INCLUDES := $(LLVM_PREBUILTS_HEADER_PATH) $(TARGET_OUT_HEADERS)/clang
 
 # Address sanitizer clang config
 ADDRESS_SANITIZER_CONFIG_EXTRA_CFLAGS := -fsanitize=address