plugins/gdk-pixbuf: Link against the shared lib (#394)
plugins/gdk-pixbuf: Link against the shared lib (#394)

The gdk-pixbuf plugin only uses public API so it can be built against
the shared library.

Tested with: `./ci.sh test -R pixbuf`
libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl,libjxl/libjxl