figure out library versioning / naming
With meson, we now produce libgtk-4.so.0.9400.0, which also has a SONAME field of libgtk-4.so.0.9400.0
The file name is fine (even though we could switch away from the interface age madness of the libtool era) but the SONAME field should really be libgtk-4.so.0, I think.