libclang/CXComment.cpp: Fix abuse of StringRef.

llvm-svn: 166163
diff --git a/clang/tools/libclang/CXComment.cpp b/clang/tools/libclang/CXComment.cpp
index 44b9473..90a67ca 100644
--- a/clang/tools/libclang/CXComment.cpp
+++ b/clang/tools/libclang/CXComment.cpp
@@ -1028,7 +1028,7 @@
   Result << "</Verbatim>";
 }
 
-static StringRef getSourceTextOfDeclaration(const DeclInfo *ThisDecl) {
+static std::string getSourceTextOfDeclaration(const DeclInfo *ThisDecl) {
   
   ASTContext &Context = ThisDecl->CurrentDecl->getASTContext();
   const LangOptions &LangOpts = Context.getLangOpts();