Fix the printing of constants.  Patch by Stepan Dyatkovskiy!

llvm-svn: 144079
diff --git a/llvm/tools/llvm-diff/DiffConsumer.cpp b/llvm/tools/llvm-diff/DiffConsumer.cpp
index c23e8fb..24b372d 100644
--- a/llvm/tools/llvm-diff/DiffConsumer.cpp
+++ b/llvm/tools/llvm-diff/DiffConsumer.cpp
@@ -64,6 +64,10 @@
     }
     return;
   }
+  if (dyn_cast<Constant>(V)) {
+    out << *V;
+    return;
+  }
 
   unsigned N = contexts.size();
   while (N > 0) {