Fix the initial ref count for WeakRealmNotifier
Fix the initial ref count for WeakRealmNotifier

Adding the run loop source to the run loop retains it, so the initial refcount
should be 0, not 1.

Shaddix/realm-dotnet,realm/realm-dotnet,Shaddix/realm-dotnet,Shaddix/realm-dotnet,realm/realm-dotnet,realm/realm-dotnet,Shaddix/realm-dotnet