The dgettext_safe wrapper is used in the few situations where it wasn't
possible to immediatelly tell that the msgid parameter wasn't NULL.
We can probably add some debug printing code here at some point to try
and bring bugs upstream, if it makes sense.
Some inspiration from https://github.com/xhebox/libuargp
It tried to use an __argp_basename function, which was defined to
program_invocation_short_name. The function definition should have been
gated.
This patch may be upstreamable to glibc.
