Fix opt -Werror build


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121904 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index fc7a754..9b3f379 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -49,6 +49,7 @@
                               unsigned AddrSpace) {
   assert(Size <= 8 && "Invalid size");
   unsigned Bits = 8 * Size;
+  (void)Bits;
   assert((isUIntN(Bits, Value) || isIntN(Bits, Value)) && "Invalid size");
   char buf[8];
   // FIXME: Endianness assumption.