kernel: Import vm_mmap_to_errno() from FreeBSD
kernel: Remove some HW_WDOG remains.
kernel: Remove a no longer used extern declaration.
start adding .Mt to email addresses in man pages

This covers share/man/man[1579]. It also consolidates multiple lines
into one, removes spurious double quotes in names or emails,
and changes punctuation where appropriate. The target style is:
.An Name Aq Mt name@somewhere.tdl
add .Mt to man pages in usr.bin/
add .Mt to man pages in bin/ games/ sys/ tools/