* Fixes hostvar serialization issue (#12005)
* Fixes regression in include_vars from within a role (#9498), where
we had the precedence order for vars_cache (include_vars, set_fact)
incorrectly before role vars.
* Fixes another bug in which vars loaded from files in the format of
a list instead of dictionary would cause a failure.
Fixes#9498Fixes#12005
* Speed up serialization of hostvars by simply using the internal
dictionary used for cached lookups
* Use blocking gets/puts on queues instead of spin locking
* Merge sequential implicitly created blocks
Also adds play information into the hostvars creation, to assure the
variable manager used there has access to vars and vars_files
Fixes#9501Fixes#8213Fixes#7844
