ts.c: Mask continuity counter when incrementing.

Previously, it seems, the continuity counter was incremented freely and the masking was 
done when using the counter. This is ok, but every now and then some pids would reach 
the special "pid unused" value and spawn a spurious debug message, which shouldn't 
happen with this fix

modules/demux/ts.c

@@ -885,7 +885,7 @@ static int DemuxFile( demux_t *p_demux )
         i_diff = ( i_cc - p_pid->i_cc )&0x0f;
         if( b_payload && i_diff == 1 )
         {
-            p_pid->i_cc++;
+            p_pid->i_cc = ( p_pid->i_cc + 1 ) & 0xf;
         }
         else
         {
@@ -1694,7 +1694,7 @@ static vlc_bool_t GatherPES( demux_t *p_demux, ts_pid_t *pid, block_t *p_bk )
     i_diff = ( i_cc - pid->i_cc )&0x0f;
     if( b_payload && i_diff == 1 )
     {
-        pid->i_cc++;
+        pid->i_cc = ( pid->i_cc + 1 ) & 0xf;
     }
     else
     {