Check in the generated copies of the manpages

These manpages were meant to be templated once per configure run.

Given that we're not bound by as many constants, e.g., --prefix isn't
generally changing for kyua in the base system, having to generate the
manpages each build seems slightly less than optimal.

In the event that one's build environment doesn't define $SH, the build
will also fail until this change is introduced.

Instead of jumping through hoops dealing with shells or permissions, let's
just cut to the chase and check the generated copies into the sourcebase
under usr.bin/kyua .

MFC with: r359260
Reported by: Julian Stacey <jhs@berklix.com>