Global ports customization

[Rodion Novoselov]

Hello.

I'm used to putting down customization things for ports into
/etc/make.conf file. However, I consider it to be a pretty wrong place
because /etc/make.conf is included implicitly every time make runs no
matter whether I build a port or something else. Having looked
bsd.port.mk through I've found an opportunity to add a per-port
customization via ${PORTSDIR}/${PORTORIGIN}/Makefile.local. Why
shouldn't do the same stuff for the ports collection at whole and add
something like:

.if exists(${PORTSDIR}/Makefile.local)
.include "${PORTSDIR}/Makefile.local"
.endif

to bsd.port.mk?

Best regards
Rodion Novoselov