meson: Update makedef script with the relevant changes from librsvg
Hi all,
This MR ports back the fixes made to the script in the following librsvg commits:
https://gitlab.gnome.org/GNOME/librsvg/-/commit/13cd13c616e12faf6f7709101f8e870c4074a0ee
https://gitlab.gnome.org/GNOME/librsvg/-/commit/28b95fcba6b1e6040e539e0ce60b5d32037b32fe