Add a minor missing -verify check.  Found by inspection.

llvm-svn: 132353
diff --git a/llvm/lib/VMCore/Verifier.cpp b/llvm/lib/VMCore/Verifier.cpp
index 8b89110..139e035 100644
--- a/llvm/lib/VMCore/Verifier.cpp
+++ b/llvm/lib/VMCore/Verifier.cpp
@@ -1645,6 +1645,9 @@
     Assert1(isa<ConstantInt>(CI.getArgOperand(3)),
             "alignment argument of memory intrinsics must be a constant int",
             &CI);
+    Assert1(isa<ConstantInt>(CI.getArgOperand(4)),
+            "isvolatile argument of memory intrinsics must be a constant int",
+            &CI);
     break;
   case Intrinsic::gcroot:
   case Intrinsic::gcwrite: