[arch-general] Add MIT Licence to /usr/share/licences/common

I'm in the process of adding a new package to the AUR, when I noticed that the MIT Licence - which this program is licensed under - is not available under /usr/share/licenses/common. Seeing that it's a fairly popular license that is copied by a number of packages (many of them Rust based: find /usr/share/licenses -name "*MIT*"), I think it would be beneficial if there could be a copy of the MIT license in the licenses package. I've attached a diff of my edits to licenses trunk. Note that I copied the licence file from rust/LICENCE-MIT and ran updpkgsums. Also, it seems the PHP-3.0 licence has changed, and its checksum has updated as well. -- Stephen Gregoratto