iOS-related warnings when packaging for Android

[kring]

When packaging a game for Android, we see a bunch of warnings like this:

Plugin 'Packages/com.cesium.unity/Plugins/iOS/lib/libCesiumGeospatial.a' doesn't have CPU architecture set, since it's a native plugin, valid architecture is required, skipping. UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&) Plugin 'Packages/com.cesium.unity/Plugins/iOS/lib/libCesiumUtility.a' doesn't have CPU architecture set, since it's a native plugin, valid architecture is required, skipping. UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&) Plugin 'Packages/com.cesium.unity/Plugins/iOS/lib/libsqlite3.a' doesn't have CPU architecture set, since it's a native plugin, valid architecture is required, skipping. UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)

We should see if we can tweak the .meta file settings so that the Android build doesn't think it should be pulling in these iOS files.