really used in bsd.man.mk).
Don't uselessly set MANSRC ("." is in the path by default, and there are
no ordering problems).
Fixed some other style bugs.
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
