the Point() and Linestring() functions create WKB representation of an
   object instead of an real geometry object.
   That produced bugs when these were inserted into tables.

   GIS tests fixed accordingly.
            
per-file messages:
  mysql-test/r/gis-rtree.result
Bug#38990 Arbitrary data input plus GIS functions causes mysql server crash 
    test result
  mysql-test/r/gis.result
Bug#38990 Arbitrary data input plus GIS functions causes mysql server crash 
    test result
  mysql-test/t/gis-rtree.test
Bug#38990 Arbitrary data input plus GIS functions causes mysql server crash 
    test fixed - GeomFromWKB invocations removed
  mysql-test/t/gis.test
Bug#38990 Arbitrary data input plus GIS functions causes mysql server crash 
    test fixed - AsWKB invocations added
  sql/item_geofunc.cc
Bug#38990 Arbitrary data input plus GIS functions causes mysql server crash 
     Point() and similar functions to create a proper object