Implement clang tool that converts std::string("") to std::string().

tools/clang/empty_string/Makefile

Index: tools/clang/empty_string/Makefile
diff --git a/tools/clang/empty_string/Makefile b/tools/clang/empty_string/Makefile
new file mode 100644
index 0000000000000000000000000000000000000000..d44641216e164deaa3c830690fa9c038d9f64d9e
--- /dev/null
+++ b/tools/clang/empty_string/Makefile
@@ -0,0 +1,23 @@
+# Copyright (c) 2013 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+#
+# This Makefile requires the LLVM build system. In order to build this tool,
+# please run tools/clang/scripts/build_tool.py.
+
+CLANG_LEVEL := ../..
+
+TOOLNAME = empty_string
+
+NO_INSTALL = 1
+
+include $(CLANG_LEVEL)/../../Makefile.config
+
+LINK_COMPONENTS := $(TARGETS_TO_BUILD) asmparser bitreader support mc
+USEDLIBS = clangTooling.a clangFrontend.a clangSerialization.a clangDriver.a \
+           clangRewriteFrontend.a clangRewriteCore.a clangParse.a clangSema.a \
+           clangAnalysis.a clangAST.a clangASTMatchers.a clangEdit.a \
+           clangLex.a clangBasic.a
+
+include $(CLANG_LEVEL)/Makefile
+