i18n: fix misconversion in shell scripts

i18n: fix misconversion in shell scripts

An earlier series that was merged at 2703572b3a ("Merge branch
'va/i18n-even-more'", 2016-07-13) failed to use $(eval_gettext
"string with \$variable interpolation") and instead used gettext in
a few places, and ended up showing the variable names in the
message, e.g.

    $ git submodule
    fatal: $program_name cannot be used without a working tree.

Catch these mistakes with

    $ git grep -n '[^_]gettext .*\\\$'

and fix them all to use eval_gettext instead.

Reported-by: Josh Bleecher Snyder
Acked-by: Vasco Almeida <vascomalmeida@sapo.pt>
Signed-off-by: Junio C Hamano <gitster@pobox.com>