DOCDISTFILES if defined. No impact should happen with this change.
DOCDISTFILES is introduced by rev. 1.541, to point the directory that
contains the distfiles for ports/textproc/docproj. It's good, but
we also build ports/sysutils/mkisofs during the release (if MAKE_ISOS
is defined). It is natural that cdrtools tarball is prefetched, then
copy it under ${CHROOTDIR}/usr/ports/distfiles.
As a result, DOCDISTFILES variable is somewhat abused for non-doc
tarballs; *DOC*DISTFILES is no longger appropriate name for that.
PR: 16843
PR: 34194
Submitted by: murray
MFC after: 6 days
8083cc2777