Bug b15 Player and Addressable build bug. Regression

I had to add a bunch of extra code during the last few betas to hack around the domain reload being broken and managed to get a build that worked without domain reload.

I now get the following error in b15 when building addressables.

Code (CSharp):

1. RuntimeInitializeOnLoadMethodAttribute: Is not allowed on a Generic class AddressablePrefabPool`1.DomainReload
2. UnityEditor.AddressableAssets.Settings.AddressableAssetSettings:BuildPlayerContent ()

The code, its just in a generic class that controls object pooling, nothing fancy.

Code (CSharp):

1. #if UNITY_EDITOR
2.         [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.SubsystemRegistration)]
3.         static void DomainReload()
4.         {
5.             // Clears some static lists.
6.         }
7. #endif