Basic: import SmallString<> into clang namespace

(I was going to fix the TODO about DenseMap too, but
that would break self-host right now. See PR11922.)

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149799 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseDeclCXX.cpp b/lib/Parse/ParseDeclCXX.cpp
index e1a1150..c1ebf91 100644
--- a/lib/Parse/ParseDeclCXX.cpp
+++ b/lib/Parse/ParseDeclCXX.cpp
@@ -266,7 +266,7 @@
 ///
 Decl *Parser::ParseLinkage(ParsingDeclSpec &DS, unsigned Context) {
   assert(Tok.is(tok::string_literal) && "Not a string literal!");
-  llvm::SmallString<8> LangBuffer;
+  SmallString<8> LangBuffer;
   bool Invalid = false;
   StringRef Lang = PP.getSpelling(Tok, LangBuffer, &Invalid);
   if (Invalid)