Update the /etc/make.conf entries regarding
sendmail. The instructions in the handbook
were from a time when we did not have any
OpenSSL version in the base system. Nowadays,
with different versions of OpenSSL in various
FreeBSD branches that differ in API/ABI, these
small corrections are needed because they would
be broken for stable/11 otherwise.

Thanks to Eugen Grosbein for pointing this out
and providing the lines for /etc/make.conf.

PR: 244937
Submitted by: eugen@