travis: Install gettext
travis: Install gettext

msgmerge(1) and friends are required to build libvirt, so the
corresponding package should be installed in the Travis worker.

Signed-off-by: Andrea Bolognani <3ada0bee826c753786fdbba72243dfba997094cf@redhat.com>

jfehlig/libvirt,andreabolognani/libvirt,crobinso/libvirt,olafhering/libvirt,crobinso/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,andreabolognani/libvirt,jardasgit/libvirt,zippy2/libvirt,zippy2/libvirt,libvirt/libvirt,olafhering/libvirt,eskultety/libvirt,nertpinx/libvirt,crobinso/libvirt,jardasgit/libvirt,zippy2/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,eskultety/libvirt,nertpinx/libvirt,andreabolognani/libvirt,olafhering/libvirt,eskultety/libvirt,eskultety/libvirt,jardasgit/libvirt,crobinso/libvirt,fabianfreyer/libvirt,jfehlig/libvirt,andreabolognani/libvirt,jardasgit/libvirt,olafhering/libvirt,nertpinx/libvirt,jardasgit/libvirt,nertpinx/libvirt,jfehlig/libvirt,zippy2/libvirt,libvirt/libvirt,nertpinx/libvirt,libvirt/libvirt,eskultety/libvirt,libvirt/libvirt