Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Ignore EINPROGRESS error on TCP connect(), and pick up the result of the
non-blocking connect later using select(). This case didn't trigger on
my UP test box, but did on Peter's SMP test box.

Spotted by: peter

Add a regression test for sending and writing zero bytes to sockets of
various types, as well as pipes and fifos for good measure. RELENG_6
currently passes all of these tests, but 7-CURRENT fails 0-byte writes
and sends on all stream socket types (and fifos, as they are based on
stream sockets).

Bumped into by: peter
Diagnosed by: jhb
Problem of: andre