Fix bug in initial seeking with double-buffered inputs
Fix bug in initial seeking with double-buffered inputs

This bug delayed the initial seek in case position was
changed since db server was last running. The playout was still
correct despite this bug, but this resulted in unnecessary
i/o at start.

jeremysalwen/Ecasound-LV2,jeremysalwen/Ecasound-LV2,jeremysalwen/Ecasound-LV2,jeremysalwen/Ecasound-LV2,jeremysalwen/Ecasound-LV2