Suppress an unused variable warning in -asserts builds

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128244 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/ARM/AsmParser/ARMAsmParser.cpp

@@ -460,6 +460,7 @@ public:
     Inst.addOperand(MCOperand::CreateReg(getMemBaseRegNum()));
 
     const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getMemOffset());
+    (void)CE;
     assert((CE || CE->getValue() == 0) &&
            "No offset operand support in mode 7");
   }