Catch2, ghc-filesystem, lv2 headers and VST3SDK sources preinstalled system packages can be used,
optionally and where available, to build sfizz via CMake options:
SFIZZ_USE_SYSTEM_CATCH
SFIZZ_USE_SYSTEM_GHC_FS
SFIZZ_USE_SYSTEM_LV2
SFIZZ_USE_SYSTEM_VST3SDK