[MINOR] http: *_dom matching header functions now also split on ":"

[MINOR] http: *_dom matching header functions now also split on ":"

*_dom is mostly used for matching Host headers, and host headers may
include port numbers. To avoid having to create multiple rules with
and without :<port-number> in hdr_dom rules, change the *_dom
matching functions to also handle : as a delimiter.

Typically there are rules like this in haproxy.cfg:

  acl is_foo  hdr_dom(host) www.foo.com

Most clients send "Host: www.foo.com" in their HTTP header, but some
send "Host: www.foo.com:80" (which is allowed), and the above
rule will now work for those clients as well.

[Note: patch was edited before merge, any unexpected bug is mine /willy]