MB-8531: Move #tmp_file_info{} record into common header

That record is are also needed by the spatial index.

Change-Id: I36031d47aae83b9869585fbc9a8e2ce661d6aeac
Reviewed-on: http://review.couchbase.org/27218
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>