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/Sema/SemaCodeComplete.cpp b/lib/Sema/SemaCodeComplete.cpp
index 06c1c93..7d38448 100644
--- a/lib/Sema/SemaCodeComplete.cpp
+++ b/lib/Sema/SemaCodeComplete.cpp
@@ -2474,7 +2474,7 @@
         Result.AddChunk(Chunk(CodeCompletionString::CK_Comma));
 
       if (MI->isVariadic() && (A+1) == AEnd) {
-        llvm::SmallString<32> Arg = (*A)->getName();
+        SmallString<32> Arg = (*A)->getName();
         if (MI->isC99Varargs())
           Arg += ", ...";
         else