In PKCS12_setup_mac(), do not assign p12->mac->salt->length until the allocation
of p12->mac->salt->data has actually succeeded.
In one of my trees for a long time already...
Save space in man page: err() -> errc() and combine vars.

Suggested by millert@ and schwarze@.

OK schwarze@, millert@
Check the result of sk_*_push() operations for failure.
ok doug@ jsing@
deregister; no binary change
ok jsing@ miod@