fseeko added

BlackBox/_OpenBSD_/Lin/Mod/gen-Libc/custom

@@ -16,5 +16,8 @@
 
 		PROCEDURE [ccall] lseek* (d: int; offset: off_t; whence: int): off_t;
 
+	(* XPG4 *)
+		PROCEDURE [ccall] fseeko* (stream: PtrFILE; offset: off_t; whence: int): int;
+
 	(* POSIX.1 *)
 		PROCEDURE [ccall] sigsetjmp* (VAR env: sigjmp_buf; savemask: int): int;