net: convert most of the networking stack to C++

bsd/net.cc

bsd/porting/route.cc

bsd/sys/compat/linux/linux_socket.cc

bsd/sys/kern/uipc_domain.cc

bsd/sys/kern/uipc_sockbuf.cc

bsd/sys/kern/uipc_socket.cc

bsd/sys/net/if.cc

bsd/sys/net/if_clone.cc

bsd/sys/net/if_dead.cc

bsd/sys/net/if_ethersubr.cc

bsd/sys/net/if_llatbl.cc

bsd/sys/net/if_llc.h

bsd/sys/net/if_loop.cc

bsd/sys/net/netisr.cc

bsd/sys/net/pfil.cc

bsd/sys/net/radix.cc

bsd/sys/net/raw_cb.cc

bsd/sys/net/raw_usrreq.cc

bsd/sys/net/route.cc

bsd/sys/net/rtsock.cc