Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Use = rather than == for expressions to test(1) builtin(1) in sh(1) to
comply with standards.

On modern branches there is an undocumented alias (see r219084) but on
stable/7 this is still an error.

Sponsored by: Cisco Systems, Inc.
MFC after: 3 days

Update scripts to work around two sh(1) bugs found in stable/8:
1) _x=$((_x + 1)) does not work while x=$((x + 1)) does.
2) Parameter Expansion, esp. "${x%%bar}" does not work if quoted.

Correct typos and improve some details forwarding.sh already
had in initiator, esp. related to ipfw accepting if the default
is deny.

Add an extra stat call to the "delay" function in addition to the
touch which together is still a lot faster than sleep 1 but seems
to help a lot more to mitigate the unrelated kernel race seen.

Sponsored by: Cisco Systems, Inc.

Add regression tests scripts for multi-IP FIBs exercising the send,
receive and forward path tagging packets with both the ifconfig fib
option or using ipfw, running ICMP6, TCP/v6 and UDP/v6 tests and
testing both setfib(2) as well as the SO_SETFIB socket option.

At 16 FIBs a total of over 64k return codes/replies/stati are checked,
sometimes multiple times (in different ways, e.g. the reflected request
as well as ipfw counter values).

The scripts need two or three machines to run and are thus not added
to the tools/regression framework but only to tools/test.

Sponsored by: Cisco Systems, Inc.