In order to provide build and provide the jack plugin with the prebuilt
binaries of gstreamer we distribute with releases, we can not depend
on an external dependency nor can we ship plugins linking to libraries
we don't provide.
We can also not provide jack ourselves, as it would likely cause a
mismatch with the jack daemon on the host.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4350>
GLib guarantees libintl is always present, using proxy-libintl as
last resort. There is no need to mock gettex API any more.
This fix static build on Windows because G_INTL_STATIC_COMPILATION must
be defined before including libintl.h, and glib does it for us as part
as including glib.h.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2028>