fix a couple of MLINKS issues
add .Mt to man pages in lib/
Sweep-fix comparing pointers with 0 (and assigning 0 to pointers).For better readability, don't compare pointers with 0 or assign 0to them. Use NULL instead.The change was done with coccinelle.
lib: Move the definition of WARNS into lib/Makefile.inc.
libbluetooth: Raise WARNS to 6.
Remove some unnecessary casts.
Adjust the bt_gethostbyaddr(3) prototype to match gethostbyaddr(3).
Add bluetooth userspace libraries - bluetooth(3) and sdp(3).Obtained-from: NetBSD