(1) Print out reason when port is ignored because of NO_CDROM,
RESTRICTED, IS_INTERACTIVE, (not) IS_INTERACTIVE, BROKEN,
REQUIRES_MOTIF or NO_PACKAGE.
Submitted by: obrien
(2) Add new special file in pkg/: DISPLAY. (Cf. man pkg_create)
(3) Minor bugfix in clean-depends target, which sometimes executed
"make clean" in the current directory. (Which is probably ok, but
is wrong nonetheless.)