Move a method from IdentifierTable.h out of line and remove the SmallString include.

Fix all the transitive include users.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149783 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Rewrite/Rewriter.cpp b/lib/Rewrite/Rewriter.cpp
index 464b299..3e1fd20 100644
--- a/lib/Rewrite/Rewriter.cpp
+++ b/lib/Rewrite/Rewriter.cpp
@@ -17,6 +17,7 @@
 #include "clang/AST/Decl.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Basic/SourceManager.h"
+#include "llvm/ADT/SmallString.h"
 using namespace clang;
 
 raw_ostream &RewriteBuffer::write(raw_ostream &os) const {