Handle "typeof" in Objective-C format string checking.  This previously crashed.

Yes, this came from actual code.

Fixes <rdar://problem/13557053>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179155 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 4e11b3a..8adfbd5 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -2744,6 +2744,10 @@
     return true;
 
   QualType ExprTy = E->getType();
+  while (const TypeOfExprType *TET = dyn_cast<TypeOfExprType>(ExprTy)) {
+    ExprTy = TET->getUnderlyingExpr()->getType();
+  }
+
   if (AT.matchesType(S.Context, ExprTy))
     return true;