Change license information to be SPDX compliant
Here it says that Archlinux PKGBUILDs are suppoed to use SPDX style identifiers for licenses for their packages. I noticed that the mgba package is using right now custom:MPL2
, which is incorrect. Mozilla Public License 2.0 is a recognized license by the SPDX list of licenses here. Therefore, I have created this pull request to change that.