FIFO Optimization - final summary

[Zhao Shuai]

Hi All,

This summer I worked on rewriting the FIFO(named pipe) subsystem.
The new FIFO system uses pipe implementation while previously
it is implemented as socket.

The new FIFO code passes the official regression test and the following
bugs has been eliminated: PR 76525,PR 94772,PR 76144,PR 116770.
According to my performance test, the new FIFO system increases the
throughput by 30% comparing with the old one.

I will continue to improve my code after GSoC and hope it can be merged
with the main tree.

-- 
Regards,
Zhao