Fix build rules for BuildVariables.inc in llvm-config.

Our previous rules didn't actually construct this file in the appropriate
location. It instead was creating it inside of the source tree. We now
use a custom build rule to create the proper file and include it from an
intermediate build object directory.

Change-Id: I571387a647e95e2053fc2520bcb8151cbaec422e

.gitignore

@@ -49,6 +49,3 @@ tools/lld
 tools/polly
 # Sphinx build tree, if building in-source dir.
 docs/_build
-
-# Ignore the generated BuildVariables.inc.
-tools/llvm-config/BuildVariables.inc

tools/llvm-config/Android.mk

@@ -2,44 +2,47 @@ LOCAL_PATH := $(call my-dir)
 
 LLVM_ROOT_PATH := $(LOCAL_PATH)/../..
 
-
 #===---------------------------------------------------------------===
 # llvm-config command line tool
 #===---------------------------------------------------------------===
 
-llvm_config_SRC_FILES := \
-  llvm-config.cpp \
-
-llvm_config_STATIC_LIBRARIES := \
-  libLLVMCore               \
-  libLLVMSupport            \
-
-llvm_config_LOCAL_INCLUDES := \
-  BuildVariables.inc \
-  LibraryDependencies.inc
-
-llvm_config_DEPENDENCIES := \
-  $(LOCAL_PATH)/BuildVariables.inc.in
-
 include $(CLEAR_VARS)
 
-BUILD_VARIABLES_IN  := $(LOCAL_PATH)/BuildVariables.inc.in
-BUILD_VARIABLES_OUT := $(LOCAL_PATH)/BuildVariables.inc
+llvm_config_SRC_FILES := \
+  llvm-config.cpp
 
-BuildVariables.inc:
-	sed -e 's/@ANDROID_BUILD_TOP@/$(subst /,\/,$(ANDROID_BUILD_TOP))/' < $(BUILD_VARIABLES_IN) > $(BUILD_VARIABLES_OUT)
+llvm_config_STATIC_LIBRARIES := \
+  libLLVMCore \
+  libLLVMSupport
 
 LOCAL_MODULE := llvm-config
 LOCAL_MODULE_TAGS := optional
 LOCAL_MODULE_CLASS := EXECUTABLES
 LOCAL_IS_HOST_MODULE := true
 
+# Create BuildVariables.inc dynamically from BuildVariables.inc.in
+generated_sources := $(call local-generated-sources-dir)
+GEN := $(addprefix $(generated_sources)/, \
+            BuildVariables.inc \
+        )
+
+$(GEN) : PRIVATE_PATH := $(LOCAL_PATH)
+$(GEN) : PRIVATE_CUSTOM_TOOL = sed -e 's/@ANDROID_BUILD_TOP@/$(subst /,\/,$(ANDROID_BUILD_TOP))/' < $< > $@
+$(GEN) : $(LOCAL_PATH)/BuildVariables.inc.in
+$(GEN): $(generated_sources)/%.inc : $(LOCAL_PATH)/%.inc.in
+	$(transform-generated-source)
+
+LOCAL_GENERATED_SOURCES += $(GEN)
+
+LOCAL_C_INCLUDES := $(generated_sources)
+
 LOCAL_SRC_FILES := $(llvm_config_SRC_FILES)
 LOCAL_STATIC_LIBRARIES := $(llvm_config_STATIC_LIBRARIES)
-LOCAL_INCLUDES := $(llvm_config_LOCAL_INCLUDES)
-LOCAL_ADDITIONAL_DEPENDENCIES := $(llvm_config_DEPENDENCIES)
 
 LOCAL_LDLIBS += -lpthread -lm -ldl
+LOCAL_ADDITIONAL_DEPENDENCIES := \
+  $(LOCAL_PATH)/Android.mk \
+  $(LOCAL_GENERATED_SOURCES)
 
 include $(LLVM_ROOT_PATH)/llvm.mk
 include $(LLVM_HOST_BUILD_MK)