remove File_Impl_Kind from file_linux

core/os/os2/pipe_linux.odin

@@ -13,10 +13,5 @@ _pipe :: proc() -> (r, w: ^File, err: Error) {
 	r = _new_file(uintptr(fds[0])) or_return
 	w = _new_file(uintptr(fds[1])) or_return
 
-	r_impl := (^File_Impl)(r.impl)
-	r_impl.kind = .Pipe
-	w_impl := (^File_Impl)(w.impl)
-	w_impl.kind = .Pipe
-
 	return
 }