In light of the dismal transfer times from ftp.FreeBSD.org, add a new
`PACKAGEROOT' env var which you would set to a proper mirror of
ftp.FreeBSD.org (say "export PACKAGEROOT=ftp://ftp3.FreeBSD.org"), to
fetch from an alternate place. This is easier to use than `PACKAGESITE'
for true mirrors, and can be used in your dot files across all versions
of FreeBSD.