In terminal output of man(7) documents, stop printing two extra blank

In terminal output of man(7) documents, stop printing two extra blank
lines before the NAME section and before the page footer.  While these
blank lines had a long tradition, they didn't really serve any purpose
and merely wasted screen real estate.  Besides, this makes output from
man(7) more similar to output from mdoc(7).

This commit keeps mandoc compatible with groff-current,
where G. Branden Robinson committed the same change
on June 16 (groff commit 2278d6ed).