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/StaticAnalyzer/Checkers/IdempotentOperationChecker.cpp b/lib/StaticAnalyzer/Checkers/IdempotentOperationChecker.cpp
index 2e1863c..d77d4d6 100644
--- a/lib/StaticAnalyzer/Checkers/IdempotentOperationChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/IdempotentOperationChecker.cpp
@@ -57,6 +57,7 @@
 #include "clang/AST/Stmt.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/Support/ErrorHandling.h"