configure.ac: add --with-gettext-package to avoid conflicts
configure.ac: add --with-gettext-package to avoid conflicts

telepathy-account-widgets is a submodule, so it can be included by
multiple projects. If we don't have a different per-project
GETTEXT_PACKAGE we end up with different projects shipping .mo files
supposed to be installed in the same location.

GNOME/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets