meson: don't assume gir can't be cross compiled.
The following Merge Request (MR) has been forwarded from GitHub in order to prevent the GNOME Project from losing contributions coming from un-official channels. And for contributors to not see their valuable contributions not being accounted for.
Github handle: maxice8
Body of the MR:
This is an outdated assumption that caused problems in various packages like atk, libgxps and libgit2-glib.