Prevent the SyncManager singleton from being destroyed during static destruction.
Prevent the SyncManager singleton from being destroyed during static destruction.

SyncManager needs to outlive all SyncSessions, but nothing guarantees
this at present. Preventing it from ever being destroyed is the simplest
way to get that guarantee.

realm/realm-core,realm/realm-core,realm/realm-core,realm/realm-core,realm/realm-core,realm/realm-object-store,realm/realm-object-store,realm/realm-core,realm/realm-core,realm/realm-object-store