Depend autorebase on msys arch rather than on ruby arch
Depend autorebase on msys arch rather than on ruby arch

Ruby and MSYS arch can differ. Also Mingw and MSYS can differ, but they
are the same by default. Unfortunatelly there's no exact parameter for
the MSYS arch, we could use here.

oneclick/rubyinstaller2,oneclick/rubyinstaller2,oneclick/rubyinstaller2