pulseaudio 4.0

This formula was developed independently, previous formulae may be relevant: #18838, #18199, #15866, #9226. This formula is for the same version as #22185 (ie both formulae try to achieve the same thing, but are different).

I have no idea if there's build problems on systems that lack this or that, all I know is that it works for me on my Lion machine. If it compiles, PulseAudio can be tested out by running `pulseaudio -v` and playing a wave file through it with the `paplay` command.

I seem to have fixed the link errors that look like `error: use of undeclared identifier 'lt__PROGRAM__LTX_preloaded_symbols'` that was discussed in #22185. The other `thread-local storage is unsupported for the current target` error is suppressed by not using clang and using llvm or gcc instead.