mux/wav: remove deprecated block_FifoCount use

dequeue whole fifo at once, so we don't need to poll/lock fifo with each
packet.

Also mark each block next packet NULL, as we don't reorder whole chain,
only current block. And we don't want to pass whole chain to
sout_AccessOutWrite.

modules/mux/wav.c

@@ -264,9 +264,13 @@ static int Mux( sout_mux_t *p_mux )
     p_sys->b_header = false;
 
     p_input = p_mux->pp_inputs[0];
-    while( block_FifoCount( p_input->p_fifo ) > 0 )
+
+    vlc_fifo_Lock( p_input->p_fifo );
+    block_t *p_block = vlc_fifo_DequeueAllUnlocked( p_input->p_fifo );
+    vlc_fifo_Unlock( p_input->p_fifo );
+
+    while( p_block != NULL)
     {
-        block_t *p_block = block_FifoGet( p_input->p_fifo );
         p_sys->i_data += p_block->i_buffer;
 
         /* Do the channel reordering */
@@ -275,7 +279,13 @@ static int Mux( sout_mux_t *p_mux )
                                  p_sys->i_chans_to_reorder,
                                  p_sys->pi_chan_table, p_input->p_fmt->i_codec );
 
+        /* We should not pass whole blockchain to accessoutwrite, as we only handled
+           current block channel reordering, so mark next as empty and handle next block separately
+           */
+        block_t *p_next_block = p_block->p_next;
+        p_block->p_next = NULL;
         sout_AccessOutWrite( p_mux->p_access, p_block );
+        p_block = p_next_block;
     }
 
     return VLC_SUCCESS;