Suppress -Wunused-variable in -Asserts build

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158037 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 1431ba4..186def7 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -736,6 +736,7 @@
           NewIntvs.push_back(Intv);
         }
         VNInfo *VNI = Intv->createDeadDef(Begin, getVNInfoAllocator());
+        (void)VNI;
         DEBUG(dbgs() << ' ' << PrintRegUnit(Unit, TRI) << '#' << VNI->id);
       }
     }