Applying xattrs on a symlink during checkout failed since
it was setting the xattrs on the final filename, not the
temporary name.
This made the "checkout union 1" test in test-basic.sh
fail.
https://bugzilla.gnome.org/show_bug.cgi?id=741125
When commiting a symlink we do store the uid/gid of the actual
symlink (i.e. not target). However, this was not restored
on non-user-mode checkout as it should.
This commit fixes that, and additionally it ensures xattrs
on symlinks are not set in user-mode checkout.
https://bugzilla.gnome.org/show_bug.cgi?id=741125