As of 0.40.0, Meson has the ability to initialize subprojects that are
git submodules. This removes the need for a separate script to achieve
that.
https://bugzilla.gnome.org/show_bug.cgi?id=781653
Meson looks for subprojects in subprojects/ by default. Since Autotools
is no longer a resident here, the submodule should be moved to the
subdirectory, instead of being linked to.
https://bugzilla.gnome.org/show_bug.cgi?id=780501