Add some constness to avoid some warnings.
Remove use register keyword.
Deal with missing/unneeded extern/prototypes.
Some minor type changes/casts to avoid warnings.
Reviewed by: md5
is wrong, even though our C compiler doesn't understand that exit() eats
control of the program, and as such can sometimes complain that main() reaches
the bottom of its body without an explicit return().
Aside from that, the functional usefulness of changing it is effectively nil,
so back it out.
Submitted by: mike
