dmo: use VLC_TS_INVALID (refs #3135)

modules/codec/dmo/dmo.c

@@ -851,10 +851,11 @@ static void *DecBlock( decoder_t *p_dec, block_t **pp_block )
     p_block = *pp_block;
 
     /* Won't work with streams with B-frames, but do we have any ? */
-    if( p_block && p_block->i_pts <= 0 ) p_block->i_pts = p_block->i_dts;
+    if( p_block && p_block->i_pts <= VLC_TS_INVALID )
+        p_block->i_pts = p_block->i_dts;
 
     /* Date management */
-    if( p_block && p_block->i_pts > 0 &&
+    if( p_block && p_block->i_pts > VLC_TS_INVALID &&
         p_block->i_pts != date_Get( &p_sys->end_date ) )
     {
         date_Set( &p_sys->end_date, p_block->i_pts );