1. Fix #692 in the kernel.

2. ss_skb_init_for_xmit() initializes forwarded skbs;

3. Protect tcp_v4_connect() -> tcp_connect() by the socket lock to let it
   finish it's operation before getting response (e.g. ACK) from the peer
   (crucial for loopback connections sending packets just by function calls);

4. Add assertions to guarantee that socket lock is aquired by current CPU;

5. Many replacements of BUG() assertions by WARN_ON_ONCE() for better
   reliability.

6. Define TFW_CLASSIFIER_ACCSZ in dependence on CONFIG_DEBUG_LOCK_ALLOC
   and several other minor fixes and cleanups;

I reviewed UDP/datagram code as well and the patch introduces several
fixes applicable to datagrams (e.g. skb_morph()), so I believe #615 can be safely closed.

Author: krizhanovsky