Merge branch 'tb/mingw-rmdir-symlink-to-directory'

Windows rmdir() equivalent behaves differently from POSIX ones in
that when used on a symbolic link that points at a directory, the
target directory gets removed, which has been corrected.

* tb/mingw-rmdir-symlink-to-directory:
  mingw: align symlinks-related rmdir() behavior with Linux

diff --cc t/test-lib.sh
Simple merge