MFC r180828
MFC r180828

Add hash table lookup for a fully connected raw sockets.

This gives significant performance improvements when many raw sockets used.
Benchmarks of mpd handeling 1000 simultaneous PPTP connections show up to 50%
performance boost. With higher number of connections benefit becomes even
bigger. PopTop snd others should also get some benefits.

MFC r180833, r180874

According to in_pcb.h protocol binding information has double locking.
It allows access it while list travercing holding only global pcbinfo lock.
This relaxed locking noticably increses receive socket lookup performance.

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