(1) New variable MAKE_ARGS: will be appended to build/install make argument

(1) New variable MAKE_ARGS: will be appended to build/install make argument
    list.  The old MAKE_FLAGS was a little hard to use since it had a weird
    default ("-f").
Suggested by:	Shigeyuki FUKUSHIMA <shige@kuis.kyoto-u.ac.jp>

(2) Add new targets clean-restricted and clean-for-cdrom, which will
    delete RESTRICTED and NO_CDROM packages and distfiles from the top.
Reviewed by:	jkh

(3) Add depends to list of things to recurse on.  It will help people
    who are trying to fetch some ports plus their dependencies.

Requested by:	Chris Dillon <cdillon@wolves.k12.mo.us>