Attempt to fix build on older libavcodec versions

video/decode/lavc_dr1.c

@@ -42,6 +42,7 @@
 #include "config.h"
 
 #include "lavc.h"
+#include "video/decode/dec_video.h"
 
 #if HAVE_PTHREADS
 #include <pthread.h>

video/decode/vdpau_old.c

@@ -31,6 +31,7 @@
 #include "video/fmt-conversion.h"
 #include "video/vdpau.h"
 #include "video/hwdec.h"
+#include "video/decode/dec_video.h"
 
 struct priv {
     struct mp_vdpau_ctx        *mpvdp;