libwebsockets

unix: sul schedule rename internal api and call regardless of existing timeout

Pre-sul, checking for interval to next pending scheduled event was expensive and
iterative, so the service avoided it if the wait was already 0.

With sul though, the internal "check" function also services ripe events and
removes them, and finding the interval to the next one is really cheap.

Rename the "check" function to __lws_sul_service_ripe() to make it clear it's
not just about returning the interval to the next pending one.  And call it
regardless of if we already decided we are not going to wait in the poll.

After https://github.com/warmcat/libwebsockets/pull/1745