Lock mdnsresponder to gcc.

Bug: 21782759

uds_daemon.c explicitly dereferences a non-volatile null pointer.
Clang rather unhelpfully says "I know what you're trying to do, but
I'm going to optimize it away anyway". There's no way to disable this
behavior, so just stick with gcc.

Change-Id: I89e905eb9144abc2fd569db5f31273b84155049b
1 file changed