2.2 candidate (and -stable too actually, who does that?) Reviewed by: Warner Losh
for gcc >= 2.5 and no-ops for gcc >= 2.6. Converted to use __dead2 or __pure2 where it wasn't already done, except in math.h where use of __pure was mostly wrong.
Note: XNSrouted and routed NOT imported here, they shall be imported with usr.sbin.
