bug#62992: Stray po.go file

[Andreas Enge]

This is not related to the dancefloor. Someone on IRC mentioned that
"make clean-go" leaves a stray file guix/build/po.go.

I suppose that it should be added to Makefile.am in the line
that currently reads:
GOBJECTS = $(MODULES:%.scm=%.go) guix/config.go $(dist_noinst_DATA:%.scm=%.go)

but would like to leave it to the experts.

Actually further above we have this:
MODULES_NOT_COMPILED =                          \
  guix/build/po.scm                             \
  guix/man-db.scm

So maybe a better fix would be to move guix/build/po.scm to MODULES
instead, since apparently it is compiled.

Andreas