[arch-general] How to get libasound_module_pcm_jack.so

Any idea where to find libasound_module_pcm_jack.so or how to compile alsa to get it? It's probably of no use to the majority of arch users but it's a module that has to be enabled by hand in asoundrc anyway, so I think it wouldn't hurt to make it available for those that find it useful. Philipp