2a0ce8a57f
defined by the C library for the various m68k ports by borrowing
some #ifs from the i386 port.
Also, align sun2 with the other m68k ports as to whether they
define __bswap{16,32} or bswap{16,32} in their C library (all
now define the __ variants).
This should make the m68k ports build sys/rump again, except
for sun2 which hits another problem later on.