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/Driver/Arg.cpp b/clang/lib/Driver/Arg.cpp
index 39b7e55..c0a2a50 100644
--- a/clang/lib/Driver/Arg.cpp
+++ b/clang/lib/Driver/Arg.cpp
@@ -61,7 +61,7 @@
 }
 
 std::string Arg::getAsString(const ArgList &Args) const {
-  llvm::SmallString<256> Res;
+  SmallString<256> Res;
   llvm::raw_svector_ostream OS(Res);
 
   ArgStringList ASL;
@@ -94,7 +94,7 @@
     break;
 
   case Option::RenderCommaJoinedStyle: {
-    llvm::SmallString<256> Res;
+    SmallString<256> Res;
     llvm::raw_svector_ostream OS(Res);
     OS << getOption().getName();
     for (unsigned i = 0, e = getNumValues(); i != e; ++i) {