dxva: Include last the internal header

It redefines _WIN32_WINNT, possibly causing problems with the
w32pthreads.h header.

libavcodec/dxva2_h264.c

@@ -20,11 +20,15 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#include "dxva2_internal.h"
 #include "h264.h"
 #include "h264data.h"
 #include "mpegutils.h"
 
+// The headers above may include w32threads.h, which uses the original
+// _WIN32_WINNT define, while dxva2_internal.h redefines it to target a
+// potentially newer version.
+#include "dxva2_internal.h"
+
 struct dxva2_picture_context {
     DXVA_PicParams_H264   pp;
     DXVA_Qmatrix_H264     qm;

libavcodec/dxva2_hevc.c

@@ -22,9 +22,13 @@
 
 #include "libavutil/avassert.h"
 
-#include "dxva2_internal.h"
 #include "hevc.h"
 
+// The headers above may include w32threads.h, which uses the original
+// _WIN32_WINNT define, while dxva2_internal.h redefines it to target a
+// potentially newer version.
+#include "dxva2_internal.h"
+
 #define MAX_SLICES 256
 
 struct hevc_dxva2_picture_context {

libavcodec/dxva2_mpeg2.c

@@ -21,10 +21,14 @@
  */
 
 #include "libavutil/log.h"
-#include "dxva2_internal.h"
 #include "mpegutils.h"
 #include "mpegvideo.h"
 
+// The headers above may include w32threads.h, which uses the original
+// _WIN32_WINNT define, while dxva2_internal.h redefines it to target a
+// potentially newer version.
+#include "dxva2_internal.h"
+
 #define MAX_SLICES 1024
 struct dxva2_picture_context {
     DXVA_PictureParameters pp;

libavcodec/dxva2_vc1.c

@@ -20,11 +20,15 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#include "dxva2_internal.h"
 #include "mpegutils.h"
 #include "vc1.h"
 #include "vc1data.h"
 
+// The headers above may include w32threads.h, which uses the original
+// _WIN32_WINNT define, while dxva2_internal.h redefines it to target a
+// potentially newer version.
+#include "dxva2_internal.h"
+
 struct dxva2_picture_context {
     DXVA_PictureParameters pp;
     DXVA_SliceInfo         si;