net/dtcpclient: Revert SSL, fix DF to use libmd
It turns out that dtcpclient's makefile checks the OPSYS and links
with either libcrypto or libmd depending on its value. The SSL
dependency is incorrect for FreeBSD, but correct for DF. Revert the
previous commit and make DragonFly link with libmd as well.
Reported by: Hajimu UMEMOTO