Define property to enable Xamarin.Mac API analysis in the IDE

[Therzok]

Over at monodevelop we have included a new MSBuild property that's included in the project. This is used to enable Xamarin.Mac API availability analyzers in the source code.

Details on how here: mono/monodevelop@5c5a62c

[CartBlanche]

@Therzok Just to be 100% sure, we need to add mono/monodevelop@5c5a62c#diff-1f3462f1373425a15290625aac5dcb5fR61 to our proppy project files?

[Therzok]

Yes, that's all you need. We target 10.12 now, so just add <XamarinMacAnalyzerMinimumOSVersion>10.12</XamarinMacAnalyzerMinimumOSVersion>. That should flag API usages for APIs not available in the deployment target.