share/man: Move many manpages to more correct packages

At the moment, all the manpages in share/man are in the utilities-man
package. Move some of them to the package they should actually be in,
using the new MANGROUPS feature.

Move all of section 3 to clibs-man. Although some of these are from
/usr/include/sys rather than libc, you can't practically use them
without libc, and clibs-man is where the libc manpages live already.

Move all of sections 4 and 9 to a new kernel-man package, except for
atf-test-case.4 which goes to tests-man. atf-test-case.4 is in the
wrong section, but this needs to be fixed upstream.

kernel-man requires special handling in generate-ucl.lua since it's
got a -man suffix but doesn't want the ' (manual pages)' automatic
suffix. For now, fix this by adding a list of packages that don't
get automatic suffixes.

Reviewed by: ifreund_freebsdfoundation.org, manu, emaste
Differential Revision: https://reviews.freebsd.org/D51504