intltool: Update to version 0.51.0

intltool: Update to version 0.51.0

- Update from 0.40.5 (2008) to 0.51.0 (2015 - latest release)
- Update of rootfile3 not required
- Changelog is too long to include here
   Changes from version 0.41.0 to 0.51.0 can be found at https://launchpad.net/intltool/+download
    and in the ChangeLog files in the Source Tarballs
   Changes prior to 0.41.0 can be found at https://download.gnome.org/sources/intltool/
    in the ChangeLog files in the Source Tarballs

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>