[SystemZ]  Remember to cast value to void to disable warning.

Hopefully fixes buildbot problems.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353898 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp b/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
index f0e9d38..a963638 100644
--- a/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
+++ b/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
@@ -1549,8 +1549,8 @@
     EVT VT = Node->getValueType(0);
     unsigned Start, End;
     unsigned BitWidth = VT.getSizeInBits();
-    bool Success = SystemZTargetLowering::analyzeFPImm(Imm, BitWidth,
-                       Start, End, static_cast<const SystemZInstrInfo *>(TII));
+    bool Success = SystemZTargetLowering::analyzeFPImm(Imm, BitWidth, Start,
+              End, static_cast<const SystemZInstrInfo *>(TII)); (void)Success;
     assert(Success && "Expected legal FP immediate");
     SDLoc DL(Node);
     unsigned Opcode = (BitWidth == 32 ? SystemZ::VGMF : SystemZ::VGMG);