Use CK_BitCast for member function pointer casts. Fixes PR5138.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@84438 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExprConstant.cpp b/lib/CodeGen/CGExprConstant.cpp
index 7f540c3..fc3748c 100644
--- a/lib/CodeGen/CGExprConstant.cpp
+++ b/lib/CodeGen/CGExprConstant.cpp
@@ -542,7 +542,11 @@
         return CS;
       }          
     }
-        
+
+    case CastExpr::CK_BitCast: 
+      // This must be a member function pointer cast.
+      return Visit(E->getSubExpr());
+
     default: {
       // FIXME: This should be handled by the CK_NoOp cast kind.
       // Explicit and implicit no-op casts