Revert "fix memory leak in free_res"

This reverts commit 94659d3.

see #39 (comment)

Author: ygrek

bindings/ffi_bindings.ml

@@ -273,9 +273,6 @@ module Bindings (F : Cstubs.FOREIGN) = struct
 
   (* Blocking API *)
 
-  let mysql_free_result = foreign "mysql_free_result"
-    (res @-> returning void)
-
   let mysql_real_connect = foreign "mysql_real_connect"
     (mysql @-> ptr_opt char @-> ptr_opt char @->
      ptr_opt char @-> ptr_opt char @-> uint @-> ptr_opt char @-> ulong @->

lib/nonblocking.ml

@@ -644,7 +644,6 @@ module Make (W : Wait) : S with type 'a future = 'a W.IO.future = struct
       let raw = stmt.Common.Stmt.raw in
       let start = handle_free (B.mysql_stmt_free_result_start raw) in
       let cont s = handle_free (B.mysql_stmt_free_result_cont raw s) in
-      let () = match stmt.Common.Stmt.meta with None -> () | Some { res; _ } -> B.mysql_free_result res in
       nonblocking stmt.Common.Stmt.mariadb (start, cont)
 
     let reset stmt =