MSYS2 PKGBUILD

When troubleshooting other code, I didn't feel like manually maintaining another build of libfunc to try to build it on msys2 again on my new install, so I whipped up a quick pkgbuild: https://gist.github.com/rpavlik/351b49579e829d0916eb74e3313c3029

Based mostly on https://github.com/Alexpux/MINGW-packages/blob/master/mingw-w64-PKGBUILD-templates/PKGBUILD.CMake-github-git with some bits (pkgver in particular) from https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=osvr-libfunctionality-git

Not sure how we want to maintain this, integrate this, or pass this to msys2 upstream, but I wanted to stick it somewhere to keep track of it.

首先阅读链接的 gist，并将其与所引用的 MSYS2 CMake PKGBUILD 模板和 Arch PKGBUILD 进行比较。确定这个仓库应该维护该软件包，还是将其移交给 upstream；要视为完成，必须确定双方同意的维护归属和集成路径，而 issue 尚未对此作出说明。