Commit Briefs
Do not treat ar_h_errno == NO_DATA as error (backport)
OpenBSD's asr returns ar_h_errno == NO_DATA when it had a fallback from UDP to TCP, so I should tolerate it as well.
DKIM follow CNAME and improve logging.
RFC 6376 doesn't care about CNAME, anyway it exists in real world.
prevent dkim_ar_cat from lose last character
It losed the last character when the length resulted string was multiple of 256
Improve serialization of AR header
Here two fixes: (1) avoid loop when checkpoint starts from whitespace, and (2) avoid infintity loop on very long last field.
Handle spaces in key-p-tag correctly.
Reported by Mischa Peters.