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/AST/DumpXML.cpp b/lib/AST/DumpXML.cpp
index 3ce02b0..dcbc518 100644
--- a/lib/AST/DumpXML.cpp
+++ b/lib/AST/DumpXML.cpp
@@ -223,7 +223,7 @@
   //---- General utilities -------------------------------------------//
 
   void setPointer(StringRef prop, const void *p) {
-    llvm::SmallString<10> buffer;
+    SmallString<10> buffer;
     llvm::raw_svector_ostream os(buffer);
     os << p;
     os.flush();
@@ -239,7 +239,7 @@
   }
 
   void setInteger(StringRef prop, unsigned n) {
-    llvm::SmallString<10> buffer;
+    SmallString<10> buffer;
     llvm::raw_svector_ostream os(buffer);
     os << n;
     os.flush();