[RFC] Seeking Approval: include bsd.port.pre.mk so SRC_BASE is defined before referenced

[Mark Linimon]

Thanks for doing this work.  A quick review looks to me to be TRT.

I would suggest some minor fixes but only for style: for me, it makes
it a bit clearer what's going on if the pre.mk include isn't among
the various WITH_* definitions, e.g. net/skystar2.  Or maybe just
having a blank line before the inclusion would help.

Also, for sysutils/fusefs-kmod, I would do the following:

 - move the MAKE_ENV= definition past the bsd.ports.pre.mk inclusion
 - throw the SRC_BASE?= line away.

mcl