page numbering in .TC in mm macros

[Pascal Stumpf]

Since groff 1.21, the .TC macro in mm uses the mm page number (\\n[P]
instead of \\n[%]):

http://cvs.savannah.gnu.org/viewvc/groff/contrib/mm/m.tmac?root=groff&r1=2.38&r2=2.39

This causes confusion with the default cover file, ms.cov, which resets
the page number using .bp 1, so that the numbering is always off by one
in the ToC (actual page 1 is page 2 in ToC, and so on ...). Should
ms.cov contain something like .nr P 1 to reset *both* numberings and
eliminate inconsistent/unexpected behaviour?

Cheers,
Pascal