clang/utils/TableGen/ClangAttrEmitter.cpp: Fix abuse of StringRef (from getValueAsString()).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@159662 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/ClangAttrEmitter.cpp b/utils/TableGen/ClangAttrEmitter.cpp
index dc58b27..794739b 100644
--- a/utils/TableGen/ClangAttrEmitter.cpp
+++ b/utils/TableGen/ClangAttrEmitter.cpp
@@ -789,7 +789,7 @@
     OS << "void " << R.getName() << "Attr::printPretty("
        << "llvm::raw_ostream &OS, ASTContext &Ctx) const {\n";
     if (Spellings.begin() != Spellings.end()) {
-      StringRef Spelling = (*Spellings.begin())->getValueAsString("Name");
+      std::string Spelling = (*Spellings.begin())->getValueAsString("Name");
       OS << "  OS << \" __attribute__((" << Spelling;
       if (Args.size()) OS << "(";
       if (Spelling == "availability") {