[php-src] PR #23669: Fixed bug GH-22981 (unix socket connect fails with EAGAIN when listen backlog is full)

Pull Request: https://github.com/php/php-src/pull/23669 Author: shoutoutuoadi325 Fixes GH-22981. php_network_connect_socket() runs the connect with the socket in non-blocking mode so it can honour the timeout. The flip side is that connect() to a unix domain socket returns EAGAIN as soon as the listen backlog fills up, while a blocking connect would wait for a slot. Short bursts of connections (PDO over a unix socket in the report) then fail with "Resource temporarily unavailable". Retry the connect every 10ms while it keeps returning EAGAIN, bounded by the connect timeout if one was given, matching what a blocking connect does. Everything else (other errors, async connects, TCP) is unchanged. gh22981.phpt runs a server with backlog=1 that starts accepting late: connect #3 fails before the patch, all 20 succeed after.