support for msys2 installations on win64

[planthaber]

"msys2" (https://msys2.github.io/) is a build environment for mingw on windows that includes a package manager (based on cygwin and mingw)

[planthaber]

I don't really know what to do here, msys2 internally avoids symlinks and is doing a copy instead, so at the second execution, FileUtils.ln_sf throws Errno::EEXIST.

Ignoring the call leads to non-updating autoproj/remotes folders, deleting them works, but local changes could be lost

[goldhoorn]

What if you use the windows way?

         Dir.create_junction(to, from)

[planthaber]

This function is available in the win32-dir gem, but sadly, that is not compatible with msys2.

[goldhoorn]

@doudou: do you want a rebase against autobuild2.0 otherwise 👍 for merge

[doudou]

@doudou: do you want a rebase against autobuild2.0

Against autoproj-2.0, yes. I'm not going to release any new 1.x release (well, probably one, but with zero new functionality, just avoiding auto-update to autoproj 2.0)

[goldhoorn]

@planthaber: can you update this PR?

[planthaber]

It is on the agenda, but Autoproj 2 moved a lot of changed functions to separate files which makes merging more difficult as i have to find the new locations first