Fix an off-by-one error in feed_monotostereo16() that caused the first sample in the buffer to be ignored. The bug caused a repetitive glitch in one of the stereo channels when playing mono sound on configurations that use the monotostereo16 feeder.
Fix an off-by-one error in feed_monotostereo16() that caused the
first sample in the buffer to be ignored. The bug caused a repetitive
glitch in one of the stereo channels when playing mono sound on
configurations that use the monotostereo16 feeder.

Reviewed by:	orion

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase