Bug#1118780: gtk4: Mipmap tests fail 16/32-bit pixel format conversions due to memory alignment issues

[Gregor Riepl]

> I have tested your patch now and it seems it just reduced the number of failures by one.

Great that it worked - although there's apparently a better way to do this: https://gitlab.gnome.org/GNOME/gtk/-/issues/7801#note_2586231

I did expect that it would only resolve that one test.

All the other errors are caused by this:

stderr:
Target has no JIT support

(test program exited with status code 1)