Removing the LockHasClients(); this code was copied from the "httpd"
output plugin, but unlike "httpd", the SnapCast output plugin does not
feed silence while paused, so we need to implement a delay to avoid
busy-looping the CPU.

As a side effect, this eliminates the suttering after resuming
playback, because the timer now gets reset even if there is a client.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1394