From Peter Fales <[email protected]>: support for Linux ARCNET,

From Peter Fales <[email protected]>: support for Linux ARCNET,
which supplies different headers from BSD ARCNET, and fixes to the
ARCNET code generator (the protocol ID field is 1 byte, so the values
for it shouldn't be byte-swapped).

Whitespace cleanups.

The "NetBSD-style" ARCNET headers are used in other BSDs as well, so
just call them "BSD-style".