Update dirdeps.mk et al to latest

dirdeps.mk and meta.autodep.mk will now look for
Makefile.depend.options
to handle optional dependencies, the work is all done by
dirdeps-options.mk

Also update to latest meta.stage.mk and gendirdeps.mk

Reviewed by: bdrewery
Differential Revision: https://reviews.freebsd.org/D15701