Use msys login shell for pacman and makepkg-mingw.
Use msys login shell for pacman and makepkg-mingw.

This ensures, that PATH and other envvars are set, so that
perl modules (and possibly others) are found.

larskanis/rubyinstaller2,oneclick/rubyinstaller2,larskanis/rubyinstaller2,oneclick/rubyinstaller2,oneclick/rubyinstaller2,larskanis/rubyinstaller2