Mark unbundled mac apps as unsupported

We do no track all the various possible issues arising from using
unbundled Mac apps.  Users may choose to use KiCad this way but issues
must be recreated on a supported configuration

libs/kiplatform/osx/app.mm

@@ -32,8 +32,13 @@ bool KIPLATFORM::APP::Init()
 
 bool KIPLATFORM::APP::IsOperatingSystemUnsupported()
 {
-    // Not implemented on this platform
+    // We only support bundled applications.  Purposefully unbundling may introduce
+    // issues that we cannot support
+#ifdef __MACOSX_APP__
     return false;
+#else
+    return true;
+#endif
 }