Implicit declaration of function 'warnc'

[Robert Scheck]

Commit fbc33757884fada818c04cd542123c809f867a52 leads to a build failure here:

main.c: In function 'repo_cleanup':
main.c:1471:5: error: implicit declaration of function 'warnc' [-Werror=implicit-function-declaration]
     warnc(e->fts_errno, "fts_read %s", e->fts_path);

[Claudio Jeker]

Guess this should be replaced with a warnx using strerror.

[Claudio Jeker]

I committed a change to use warnx + strerror into OpenBSD. Tomorrow this should be available in the rpki-client-openbsd repo.

[Claudio Jeker]

Checked with Travis CI, this should be fixed now.