Log Message:
libopenmpt: update to 0.6.6.

### libopenmpt 0.6.6 (2022-09-25)

 *  [**Sec**] Possible crash when playing manipulated IT / MPTM files with a T00
    command. (r17789)

 *  MTM: In MultiTracker, setting speed and tempo are mutually exclusive
    commands. Still, some MultiTracker modules were made to be played with
    external players such as DMP, so they actually rely on "standard" \ 
speed /
    tempo behaviour. Decide which behaviour to use by checking of speed and
    tempo commands are found on the same row.
 *  MTM: Ignore sample loops if the loop end is <= 2.
 *  Echo DMO: Migrate left and right delay values in modules made with OpenMPT
    versions between 1.27.01.00 and 1.30.05.00 to the correct interpretation.

 *  FLAC: Update to v1.4.1 (2022-09-22).

### libopenmpt 0.6.5 (2022-08-21)

 *  [**Bug**] `Makefile` now also uses `CC`, `CXX`, `LD`, and `AR` when set as
    environment variables.
 *  [**Bug**] libopenmpt can now be built to target macOS down to version 10.13
    again.

 *  [**New**] `Makefile` now uses `PKG_CONFIG` as path to `pkg-config`.

 *  DBM: Sample middle-C frequencies were slightly off.
    laffik_-_marynarze.dbm sounds much more bearable now.
 *  DBM: Fixed pattern break parameter interpretation.
 *  Echo DMO: Setting the delay parameter to 0 yielded a 2-second echo delay
    instead of 1ms.
 *  Digi Booster Echo: Setting the delay parameter to 0 yielded a 510ms echo
    delay instead of approximately 334ms.

 *  mpg123: Update to v1.30.2 (2022-08-01).