community/jack2: arm patch

ARM does not like packed structures. Probably. But with one small patch
jack works. Patch from https://github.com/AutoStatic/jack-armel.
newline on EOF
community/jack2: proper PKGBUILD

Few changes, it's closer to what pkgbuild should look like.
communty/jack2: pkgrel up to 3.1
Merge pull request #511 from j000/master

Community/Jack2 arm patch