[arch-multilib] Addition of jack2-multilib and multilib push perms

Hi guys I want to add a 'jack2-multilib' to the repo, as an equivalent to 'lib32-jack'. This would allow users to continue using or to install 'jack2' while using a package requiring a 32-bit library of 'jack'. As it is currently, some multilib users are forced to use 'jack' even if they want to use 'jack2'. As there is no simple way to simply build in parts, 'jack2-multilib' replaces 'jack2' in a multilib installation. Even if there were, this would be the better approach since the software already contains a specific flag to build a "mixed" or hybrid jack. In light of this, I would also like the appropriate permissions to be able to push packages to [multilib]. Caveat: I'm not a multilb user. -- GPG/PGP ID: C0711BF1