libclang: introduce cxstring::createNull()

llvm-svn: 174173
diff --git a/clang/tools/libclang/CXString.cpp b/clang/tools/libclang/CXString.cpp
index 739646b..030e34c 100644
--- a/clang/tools/libclang/CXString.cpp
+++ b/clang/tools/libclang/CXString.cpp
@@ -29,6 +29,13 @@
 // Basic generation of CXStrings.
 //===----------------------------------------------------------------------===//
 
+CXString cxstring::createNull() {
+  CXString Str;
+  Str.data = 0;
+  Str.private_flags = CXS_Unmanaged;
+  return Str;
+}
+
 CXString cxstring::createCXString(const char *String, bool DupString){
   CXString Str;
   if (DupString) {