treewide: replace confess with croak
The PublicInbox::Eml (and previously Email::MIME) use of confess
was the primary (or only) culprit behind the lei2mail segfaults
fixed by commit
0795b0906cc81f40.
("ds: guard against stack-not-refcounted quirk of Perl 5").
We never care about a backtrace when dealing with Eml objects
anyways, so it was just a worthless waste of CPU cycles.
We can also drop confess in a few other places. Since we only
use Perl and Inline::C, users will never be without source
and can replace s/croak/Carp::confess/ on a per-callsite basis
to help report problems.
It's also possible to use PERL5OPT=-MCarp=verbose in the
environment though still potentially risky.
Link: https://public-inbox.org/meta/20210201082833.3293-1-e@80x24.org/