audio/rezound: add PulseAudio support + miscellaneous improvements
- Unbreak the build against various options with NLS disabled [*]
- Allow to build with PulseAudio support (keep off by default)
- Sprinkle some FOO_IMPLIES to ensure we don't have unregistered dependencies
- Drop MAKE_JOBS_UNSAFE added in r300554 (now commit df187e25d75f) eleven years ago for version 0.12.3beta without much rationale except rather vague "fails to build on my Q9550"; if the problem is still here, let's get new build log and reset it accordingly, but so far I could not trigger it
Reported by: William Bulley [*]