MDEV-30659 Server crash on EXPLAIN SELECT/SELECT on table with engine Aria for LooseScan Strategy

Amended patch from Monty:

The issue was that Loose_scan_opt::save_to_position() did not take
into account records_out from best_access_path()

Make sure that POSITION object filled by Loose_scan_opt::save_to_position()
has records_out not higher than any other possible access method.

sql/sql_select.h

@@ -1022,6 +1022,7 @@ public:
   */
   double read_time;
 
+  /* record combinations before this table */
   double loops;
 
   double    prefix_record_count;