Infinite loop in pvio_socket_internal_connect

(copied from PR-204) by Hugo Wen.

There's an infinite loop in function pvio_socket_internal_connect to retry connection forever if receiving specific errno number:

• No retry interval in the loop which will cause the process consuming all CPU usage and slowdown/stuck other processes.
• Even if the timeout was set in mysqladmin command option, the function will retry forever in the infinite loop.

The issue was seen a few times when MariaDB server was hanging and not accepting new connection correctly. When the issue happened mysqladmin process consumed 100% CPU usage and stack trace shows it stuck in the loop. Though --connect_timeout was set in command line, mysqladmin will never end until a force kill was executed.