The subtle part is adding .rst and .py files to vpath so they can be
used as dependencies without prefixing with $(srcdir)
We also change the interface to mkbuildeps.py: rather than getting the
containing directory from the conf file path, we go the other way.
It turns out there was a reason the old man pages were stored in a man
compatible hierarchy, namely so that we could run man on them before
installing.
Hardcode doc build location into test suite. This isn't ideal, but
let's unbreak the test suite for now.
This helps avoid build artifacts (namely, nroff and gzipped-nroff man
pages) owned by root.
The variables allow choosing which generator to use for the man page.
These will be hooked to configure in a following commit.
The python script mkdocdeps.py is used to import the list of man pages
from the sphinx configuration to make.
This will delete the (release only) target update-man-versions. This
will be replaced in a followup commit.
