Revert "MINOR: mworker: sets used or closed worker FDs to -1"

This reverts commit ea7371e934.

This can't work correctly as we need this FD in the worker to be
inserted in the fdtab. The correct way to do it would be to cleanup the
mworker_proc in the master after the fork().

src/cli.c

@@ -2982,19 +2982,11 @@ int mworker_cli_sockpair_new(struct mworker_proc *mworker_proc, int proc)
 		global.maxsock++; /* for the listening socket */
 	}
 
-	/* the sockpair was asssigned successfully to the listener for the
-	 * worker,  we can remove it from the mworker_proc, so it's not used
-	 * elsewhere accidentally
-	 */
-	mworker_proc->ipc_fd[1] = -1;
-
 	return 0;
 
 error:
 	close(mworker_proc->ipc_fd[0]);
 	close(mworker_proc->ipc_fd[1]);
-	mworker_proc->ipc_fd[0] = -1;
-	mworker_proc->ipc_fd[1] = -1;
 	free(err);
 
 	return -1;