drupal_http_request should resolve hostname of target before initiating a socket connection

The issue is linked with the feed aggregator module

Following real scenario:

Target host has a working ipv4 address and a misconfigured ipv6 address.
Since you're not doing a NS lookup before initiating a socket connection,
php resolves the ipv6 address but does not resolve the ipv4 address
which leads to a request timeout error.

How to fix:

do a NS lookup
if unsuccessful return error
open socket (stream_socket_client)
execute request
if request fails
if address is ipv6 address
do a NS lookup for the ipv4 address
open socket
execute request
if request fails
return error

File: includes/common.inc line 859+