Item_func_spatial_collection::fix_length_and_dec didn't call parent's method, so
        the maybe_null was set to '0' after it. But in this case the result was
        just NULL, that caused wrong behaviour.

per-file comments:
  mysql-test/r/gis.result
Bug #57321 crashes and valgrind errors from spatial types 
        test result updated.

  mysql-test/t/gis.test
Bug #57321 crashes and valgrind errors from spatial types 
        test case added.
  sql/item_geofunc.h
Bug #57321 crashes and valgrind errors from spatial types 
        Item_func_geometry::fix_length_and_dec() called in
        Item_func_spatial_collection::fix_length_and_dec().