vdpau/chroma: skip forward to current picture if forced (fixes #11410)

VDPAU introduces a delay of one field (one picture if not deinterlacing).
This is normally not an issue as the PTS is preserved. But it does not
work if there is only one picture not followed by another one.

(cherry picked from commit 6e82ebed93d6f017af4369d8712f7063421ee9ca)

Conflicts:
	modules/hw/vdpau/chroma.c

modules/hw/vdpau/chroma.c

@@ -478,14 +478,35 @@ static picture_t *VideoRender(filter_t *filter, picture_t *src)
         picture_Release(src);
     }
     else
+    {
         sys->history[MAX_PAST + MAX_FUTURE].field = NULL;
+        sys->history[MAX_PAST + MAX_FUTURE].force = false;
+    }
 
     if (dst == NULL)
         goto skip;
 
     vlc_vdp_video_field_t *f = sys->history[MAX_PAST].field;
     if (f == NULL)
-        goto error;
+    {   /* There is no present field, probably just starting playback. */
+        if (!sys->history[MAX_PAST + MAX_FUTURE].force)
+            goto error;
+
+        /* If the picture is forced, ignore deinterlacing and fast forward. */
+        /* FIXME: Remove the forced hack pictures in video output core and
+         * allow the last field of a video to be rendered properly. */
+        while (sys->history[MAX_PAST].field == NULL)
+        {
+            f = sys->history[0].field;
+            if (f != NULL)
+                f->destroy(f);
+
+            memmove(sys->history, sys->history + 1,
+                    sizeof (sys->history[0]) * (MAX_PAST + MAX_FUTURE));
+            sys->history[MAX_PAST + MAX_FUTURE].field = NULL;
+        }
+        f = sys->history[MAX_PAST].field;
+    }
 
     dst->date = sys->history[MAX_PAST].date;
     dst->b_force = sys->history[MAX_PAST].force;