Kleis Auke Wolthuizen authored Mar 29, 2024 and Federico Mena Quintero committed Apr 09, 2024

When building without GDK-Pixbuf, this disables the legacy pixbuf-based
C API (`rsvg_pixbuf_*`), along with these functions:
- `rsvg_handle_get_pixbuf()`
- `rsvg_handle_get_pixbuf_and_error()`
- `rsvg_handle_get_pixbuf_sub()`

Context: https://github.com/lovell/sharp-libvips/issues/226.
Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/956>