[PATCH] enabel LOG_TCP_REDIRECTS by default

We still get requests and sometimes confusion about how to identify the
squid-generated 3xx responses from upstream-generated 3xx responses.

It turns out there has long been a log status code of TCP_REDIRECT to
mark the squid-generated ones. But it required a compiler flag to
enable.

This patch seeks to remove the compiler flag and make the 3xx status
generated by Squid always use that log code. 3xx from servers or
ICAP/eCAP will continue to use TCP_MISS and other status codes.

Amos