Resolve a few more symbols at compile/link time, rather than at
run-time. This fixes the bz2 commands. We link against -lmd, so use
<md2.h> and <md5.h>, instead of <openssl/md[25].h> (why do we even
install those separately?). Bump up portrevision.

Change the reference (in the comment) from -lscrypt to -lcrypt.