Two proposals to improve resilience of the Quick-DiaSASL service

The accept() call can be handled a little better to avoid sudden death of freeDiameter in spurious cases.

The refusal of socket_server() is better to try in a loop, to offer more resilient binding to a port if it is blocked by prior use (like just after a crash). This discipline uses exponential fallback, and would pickup after 31 seconds if freeDiameter is started again right after a crash (like init does it).