mqrtmoff.com: Disables MIDI real time message output in MPU-401 intelligent mode.
By default the MPU-401 sends out MIDI clock beats on the MIDI OUT, which is not
needed for use with games and may be unwanted in complex MIDI setups where
another clock master is present.

Written with debug.com (8086 disassembly is the source code), released to the
public domain by Kimmo Kulovesi <https://github.com/arkku/> on 2019-02-12.
