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.
and multiply functions from the old libkern. The m68010 versions
are only compiled when __mc68010__ is defined, presently that's
only done when building for sun2.
Reviewed by christos.
