OpenBSD 5.0

Thank you to whoever created the version 5.0 snapshots for Mac68k.  I was
going to try it myself, but hadn't gotten very far yet.  The snapshot worked
just fine on my Performa 475.

However, in order to avoid the "env: -fno-function-cse: No such file or
directory" error when building ports, I had to revert the change made in
/usr/ports/infrastructure/mk/bsd.port.mk between version 1.963 and 1.964. I
assume there is a more elegant way, but I am not familiar enough with the
ports build system to do better.