Added code to handle BSDI's 4.3 net-2 funky uname call. Netscape was using

Added code to handle BSDI's 4.3 net-2 funky uname call.  Netscape was using
this to determine system name.  Failure of this call caused netscape to
print "uname() failed" on app startup.  Also affected netscape mail headers
and http sysname.  Code taken from FreeBSD with minor mods.  Good work
guys.  Let the world, or at the very least, netscape, know that you use
OpenBSD.  Include COMPAT_43 in kernel config to enable functionality.