If a raw zone is modified, but the dns_update_signaturesinc() call in
receive_secure_serial() fails, the corresponding secure zone's database
will not be modified, even though by that time a message containing the
bumped signed serial will already have been logged. This creates
confusion, because a different secure zone version will be served than
the one announced in the logs. Move the relevant dns_zone_log() call so
that it is only performed if the secure zone's database is modified.
(cherry picked from commit cfbc8e264d)
cdc7ab42b1