Provide option to suppress resourceUsage keys in AU plists

[Dan Korneff]

Hey @Christoph-Hart I've recently ran into issues with Pace protected plugins and Garageband. Apparently a change made a few months back block these plugins from loading. An update to JUCE was made to fix this issue. Can we merge this?

Build: Provide option to suppress resourceUsage keys in AU plists · juce-framework/JUCE@ba172bc

JUCE is an open-source cross-platform C++ application framework for desktop and mobile applications, including VST, VST3, AU, AUv3, LV2 and AAX audio plug-ins. - Build: Provide option to suppress resourceUsage keys in AU plists · juce-framework/JUCE@ba172bc

GitHub (github.com)

`SUPPRESS_AU_PLIST_RESOURCE_USAGE`
  - May be either TRUE or FALSE. Defaults to FALSE. Set this to TRUE to disable the `resourceUsage`
    key in the target's plist. This is useful for AU plugins that must access resources which cannot
    be declared in the resourceUsage block, such as UNIX domain sockets. In particular,
    PACE-protected AU plugins may require this option to be enabled in order for the plugin to load
    in GarageBand.

[Dan Korneff]

@Christoph-Hart Wanted to give this a friendly bump. Is there a way to set SUPPRESS_AU_PLIST_RESOURCE_USAGE in the latest versions?
iLok protected plugs wont load in Garageband without this.

[Christoph Hart]

Have you checked the develop branch? I migrated to JUCE 6 there so maybe this fix is already included? If not it would be good to migrate as it might be easier to merge it to JUCE 6 than to the old one from master.