Log Message:
libopenmpt: update to 0.5.4.

ChangeLog:

### libopenmpt 0.5.4 (2020-11-29)

 *  AMS: An upper bound for uncompressed sample size is now established to
    avoid memory exhaustion from malformed files.
 *  DMF: Support early format beta versions (in particular versions 1-4).
 *  MED: Also use octave wrapping in 8-channel mode for MMD0/MMD1 modules.
 *  MED: If 8-channel mode is activated, ignore BPM mode.
 *  MED: Emulate tempo commands F01 and F02 quirk.
 *  MED: Tempo commands below 32 BPM were interpreted as tempo slides.
 *  IMF: Instrument sample mapping was off by one octave, notable in the guitar
    part of Astaris by Karsten Koch.

 *  pugixml: Update to v1.11 (2020-11-26).