commit: forbid --pathspec-from-file --all

commit: forbid --pathspec-from-file --all

I forgot this in my previous patch `--pathspec-from-file` for
`git commit` [1]. When both `--pathspec-from-file` and `--all` were
specified, `--all` took precedence and `--pathspec-from-file` was
ignored. Before `--pathspec-from-file` was implemented, this case was
prevented by this check in `parse_and_validate_options()` :

    die(_("paths '%s ...' with -a does not make sense"), argv[0]);

It is unfortunate that these two cases are disconnected. This came as
result of how the code was laid out before my patches, where `pathspec`
is parsed outside of `parse_and_validate_options()`. This branch is
already full of refactoring patches and I did not dare to go for another
one.

Fix by mirroring `die()` for `--pathspec-from-file` as well.

[1] Commit e440fc58 ("commit: support the --pathspec-from-file option" 2019-11-19)

Reported-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Alexandr Miloslavskiy <alexandr.miloslavskiy@syntevo.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>