This requires some autotools magic when setting up the environment
through autogen.sh, because autoreconf does not do the right thing
by default.

The correct order for setting up localization is:

  ‣ autopoint
  ‣ aclocal
  ‣ ...

otherwise aclocal will copy the system's gettext.m4 instead of honouring
the version we specified with AM_GNU_GETTEXT_VERSION in configure.ac.