After .Sm on, spacing ought to restart right away, before the next token,

After .Sm on, spacing ought to restart right away, before the next token,
and not with a delay, after the next token.  But be careful not to cause
leading white space at the beginning of a line or column.
Improves chmod(1), ksh(1), tar(1), ps(1) and probably many more.
ok kristaps@ jmc@ sobrado@