Replace DECLARE_OBJ_CHECKERS with OBJECT_DECLARE_TYPE where the
typedefs can be safely removed.

Generated running:

$ ./scripts/codeconverter/converter.py -i \
  --pattern=DeclareObjCheckers $(git grep -l '' -- '*.[ch]')

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200831210740.126168-16-ehabkost@redhat.com>
Message-Id: <20200831210740.126168-17-ehabkost@redhat.com>
Message-Id: <20200831210740.126168-18-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>