Change 'MDecl' to 'MD' to fix redefinition compiler error in MSVC++.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@53849 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index 2f12a6f..8cceda2 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -364,9 +364,9 @@
          E = IDecl->protocol_end(); P != E; ++P)
       MergeProtocolPropertiesIntoClass(IDecl, *P);
   } else {
-    ObjCProtocolDecl *MDecl = cast<ObjCProtocolDecl>(ClassDecl);
-    for (ObjCProtocolDecl::protocol_iterator P = MDecl->protocol_begin(),
-         E = MDecl->protocol_end(); P != E; ++P)
+    ObjCProtocolDecl *MD = cast<ObjCProtocolDecl>(ClassDecl);
+    for (ObjCProtocolDecl::protocol_iterator P = MD->protocol_begin(),
+         E = MD->protocol_end(); P != E; ++P)
       MergeOneProtocolPropertiesIntoClass(IDecl, (*P));
   }
 }