Revert "Allow use of inputs without DEMUX_GET/SET_*TIME in input-slave."

This reverts commit 60106b74.
That patch isn't a correct fix for the problem.

src/input/input.c

@@ -2732,12 +2732,11 @@ static void SlaveDemux( input_thread_t *p_input )
 {
     int64_t i_time;
     int i;
-    bool b_set_time = true;
 
     if( demux_Control( p_input->p->input.p_demux, DEMUX_GET_TIME, &i_time ) )
     {
-        /* msg_Err( p_input, "demux doesn't like DEMUX_GET_TIME" ); */
-        b_set_time = false;
+        msg_Err( p_input, "demux doesn't like DEMUX_GET_TIME" );
+        return;
     }
 
     for( i = 0; i < p_input->p->i_slave; i++ )
@@ -2748,7 +2747,7 @@ static void SlaveDemux( input_thread_t *p_input )
         if( in->b_eof )
             continue;
 
-        if( b_set_time && demux_Control( in->p_demux, DEMUX_SET_NEXT_DEMUX_TIME, i_time ) )
+        if( demux_Control( in->p_demux, DEMUX_SET_NEXT_DEMUX_TIME, i_time ) )
         {
             for( ;; )
             {