/usr/ports symlink and portconf

[Rong-en Fan]

When /usr/ports is a symbolic links, ports-mgmt/portconf does
not because .CURDIR contains the real path.

I filed a PR 104838 last year which contains a patch that detects
the real path of ${PORTSDIR} at runtime. The patch is at

http://people.freebsd.org/~rafan/portconf.diff

If you look at the patch, you will find that I invoke shell (via !=)
whenever make is used. It impacts buildworld speed.
On a P4 3.4G SMP i386 box, building RELENG_6 :

before / after: 49m24.906s / 52m17.299s

If most of you don't think this is acceptable, then it can
be done at installation time.

I would like to get this committed into portconf. Some boxes of
mine has symlink on /usr/ports.

Regards,
Rong-En Fan