[Reproducers] Fix warnings without asserts

Make sure the variable is used when asserts are compiled out.

llvm-svn: 355464
diff --git a/lldb/include/lldb/Utility/ReproducerInstrumentation.h b/lldb/include/lldb/Utility/ReproducerInstrumentation.h
index f10398e..ac67899 100644
--- a/lldb/include/lldb/Utility/ReproducerInstrumentation.h
+++ b/lldb/include/lldb/Utility/ReproducerInstrumentation.h
@@ -261,6 +261,7 @@
   void HandleReplayResultVoid() {
     unsigned result = Deserialize<unsigned>();
     assert(result == 0);
+    (void)result;
   }
 
 private: