Revert "decoder: fix signal call from input_DecoderFlush"

Decoder still need to be signaled when FIFO is already empty.

This reverts commit 32040fdc.

src/input/decoder.c

@@ -1881,10 +1881,9 @@ void input_DecoderFlush( decoder_t *p_dec )
      * to display one frame */
     if( p_owner->fmt.i_cat == VIDEO_ES && p_owner->paused
      && p_owner->frames_countdown == 0 )
-    {
         p_owner->frames_countdown++;
+
     vlc_fifo_Signal( p_owner->p_fifo );
-    }
 
     vlc_fifo_Unlock( p_owner->p_fifo );
 }