* netbsd/sys/netinet/tcp_output.c: optimize mbuf allocation on output.   allocate cluster only when necessary.
* netbsd/sys/netinet/tcp_output.c: optimize mbuf allocation on output.
  allocate cluster only when necessary.

MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame