audio/fasttracker2: Update to v1.06

Changes since v1.05:

v1.06 - 15.01.2020
- Bugfix: Scopes were not doing backwards sampling correctly on pingpong loops.
  This would also affect the sample playback line in Smp. Ed. It was especially
  noticable on very low sampling rates (note).
- For devs: Added HAS_MIDI compiler pre-processor flag. If not defined, MIDI
  will not be used in the clone. Handy for situations where rtmidi and/or
  libstdc++ can't be used/compiled.

(fox)