Else when WITHOUT_SENDMAIL is set we still create a sendmail package
that contains (only) two directories.
Reviewed by: manu
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D24149
the creation of /var/spool/clientmqueue and therefore the need for the
smmsp user and group if NO_SENDMAIL is defined. This required breaking out
the creation of the directory into a new BSD.sendmail.dist mtree file.
MFC after: 1 week