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.)

llvm-svn: 149799
diff --git a/clang/lib/CodeGen/CGVTT.cpp b/clang/lib/CodeGen/CGVTT.cpp
index a8af647..34e34b2 100644
--- a/clang/lib/CodeGen/CGVTT.cpp
+++ b/clang/lib/CodeGen/CGVTT.cpp
@@ -100,7 +100,7 @@
 llvm::GlobalVariable *CodeGenVTables::GetAddrOfVTT(const CXXRecordDecl *RD) {
   assert(RD->getNumVBases() && "Only classes with virtual bases need a VTT");
 
-  llvm::SmallString<256> OutName;
+  SmallString<256> OutName;
   llvm::raw_svector_ostream Out(OutName);
   CGM.getCXXABI().getMangleContext().mangleCXXVTT(RD, Out);
   Out.flush();