Use isa<> instead of dyn_cast<> as suggested by Nick.

Should've read the patch a bit closer, sorry.

llvm-svn: 144164

llvm/tools/llvm-diff/DiffConsumer.cpp

@@ -64,7 +64,7 @@ void DiffConsumer::printValue(Value *V, bool isL) {
     }
     return;
   }
-  if (dyn_cast<Constant>(V)) {
+  if (isa<Constant>(V)) {
     out << *V;
     return;
   }