Delete the entire cleandepend/cleanmachine target thing now that its been
cleared out in r269029

Reviewed by:	emaste@freebsd.org
When producing fmake(1), `make clean' should remove fmake.1 (a copy of
make.1). Introduced initially via SVN r250699 (sjg).

Reviewed by:	sjg, gjb
MFC after:	3 days
X-MFC-to:	stable/10