gettext is sufficient

This also ends up fixing parallel builds
because intltool has a known bug. Too bad intltool
is unmaintained.

https://bugzilla.gnome.org/show_bug.cgi?id=792887

https://launchpad.net/bugs/1687644

Also remove the unnecessary Encoding=UTF-8 headers

https://wiki.gnome.org/Initiatives/GnomeGoals/GettextMigration