Build: automatically generate list of files to be translated in configure
configure is easiest option how to automatically generate POTFILES.in.
Attempts to add it to po/Makefile* have big potential to create cyclic
depedencies and cause other trouble.
Given how rare operation adding a source file is, I think it is sufficient
to document that configure needs to be run again after adding a source file
with translatable strings.
https://fedorahosted.org/freeipa/ticket/6418
Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Lukas Slebodnik <lslebodn@redhat.com>