GIS update get_copy overrides to do_get_copy const

sql/item_geofunc.h

@@ -994,7 +994,7 @@ public:
   {
     return &type_handler_geometry;
   }
-  Item *get_copy(THD *thd) override
+  Item *do_get_copy(THD *thd) const override
   { return get_item_copy<Item_func_simplify>(thd, this); }
 };
 
@@ -1040,7 +1040,7 @@ public:
     static LEX_CSTRING name= {STRING_WITH_LEN("st_isvalid") };
     return name;
   }
-  Item *get_copy(THD *thd) override
+  Item *do_get_copy(THD *thd) const override
   { return get_item_copy<Item_func_isvalid>(thd, this); }
 };
 
@@ -1060,7 +1060,7 @@ public:
   {
     return &type_handler_point;
   }
-  Item *get_copy(THD *thd) override
+  Item *do_get_copy(THD *thd) const override
   { return get_item_copy<Item_func_validate>(thd, this); }
 };
 
@@ -1345,7 +1345,7 @@ public:
     static LEX_CSTRING name= {STRING_WITH_LEN("st_latfromgeohash") };
     return name;
   }
-  Item *get_copy(THD *thd) override
+  Item *do_get_copy(THD *thd) const override
   { return get_item_copy<Item_func_latfromgeohash>(thd, this); }
 };
 
@@ -1360,7 +1360,7 @@ public:
     static LEX_CSTRING name= {STRING_WITH_LEN("st_longfromgeohash") };
     return name;
   }
-  Item *get_copy(THD *thd) override
+  Item *do_get_copy(THD *thd) const override
   { return get_item_copy<Item_func_longfromgeohash>(thd, this); }
 };
 
@@ -1380,7 +1380,7 @@ public:
     return name;
   }
   String *val_str(String *) override;
-  Item *get_copy(THD *thd) override
+  Item *do_get_copy(THD *thd) const override
   { return get_item_copy<Item_func_pointfromgeohash>(thd, this); }
 };
 

sql/item_sum.h

@@ -2162,7 +2162,7 @@ public:
     return { STRING_WITH_LEN("st_collect(") };
   }
   Item *copy_or_same(THD* thd) override;
-  Item *get_copy(THD *thd) override
+  Item *do_get_copy(THD *thd) const override
   { return get_item_copy<Item_func_collect>(thd, this); }
 
   bool supports_removal() const override