Remove bad logic for old bonjour with Xeme

Old bonjour is not going to be ported to xeme so this check was no longer
necessary, but it was giving false positives anyways causing us to try and
build bonjour when we don't have avahi including on macOS.

Testing Done:
Ran with the turtles and ran on macOS with the homebrew native file and built successfully.

Reviewed at https://reviews.imfreedom.org/r/3020/