Remove the outdated casts to "char *" from the setsockopt(2),

Remove the outdated casts to "char *" from the setsockopt(2),
write(2), and getipnodebyaddr(3) calls.  Now all the above functions
accept "void *" in that arguments and have prototypes.  Thus, the
casts are useless under the normal circumstances (and would be harmful
if the functions had no prototypes.)

MFC after:	2 weeks