This update for multimon-ng fixes the following issues:

- Update to new upstream release 1.2.0
  * Separated FLEX and FLEX_NEXT. The former is identical to 1.1.9,
    while FLEX_NEXT gained new features, as well as known
    regressions. (See #168)
  * Fix CVE-2020-36619 (boo#1206542)
  * Several smaller POCSAG fixes.
  * Fix for opening large wav files with improper header.