Socket address to pathname translation

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When socket address is submitted to sysmask for access control check, the
address is translated to the unix pathname syntax then checked in the same
way as for other pathnames.

The translated pathname is as follows.

/request/protocol/address

Where request corresponds to the nature of the system call, and is one of
the following:

bind listen accept connect setsockopt send

and the protocol is one of the following:

tcp
udp
ipv4	(raw ip socket)
local	(local unix domain socket)

For local protocol, the address is the unix pathname of the socket, or empty
if the socket is unnamed.

For tcp and udp protocol, the address is the as follows

ip1.ip2.ip3.ip4/port

And for ipv4, only the ip address is present.

For example, the following corresponds to a http connection request to
localhost.

/connect/tcp/127.0.0.1/80