[arch-proaudio] New [community] additions for 2018

[Ralf Mardorf]

Now that rtirq moved from AUR to community, it's to consider to what
kernel rtirq should fit. OTOH I used and still use the current release
of rtirq with several kernel releases. At the moment there shouldn't be
an issue with all common used kernel releases. In my experiences it
works with all 4.x releases and it even should work with many 3.x
releases, at least I didn't experience an issue around the last 3 years.
However, in the past there where a few issues, the release model distro
Ubuntu Studio shipped with a rtirq release that didn't fit to the
provided "lowlatency" kernel. This couldn't happen to us, but we could
run into a mainline vs LTS kernel issue. In my opinion rtirq should fit
to the mainline kernel, if it can't be used for all provided kernels.