Update third_party/libva to version 1.7.1

third_party/libva/va/va_enc_h264.h

Index: third_party/libva/va/va_enc_h264.h
diff --git a/third_party/libva/va/va_enc_h264.h b/third_party/libva/va/va_enc_h264.h
index 02818d1c66ca5f6da40a21c14985c1a5b00cbc11..8ec18ea33f2bd81bff90f064d73f255c0af07f3b 100644
--- a/third_party/libva/va/va_enc_h264.h
+++ b/third_party/libva/va/va_enc_h264.h
@@ -121,7 +121,7 @@ typedef enum {
 } VAEncPackedHeaderTypeH264;
 
 /**
- * \brief Sequence parameter for H.264 encoding in baseline, main & high 
+ * \brief Sequence parameter for H.264 encoding in baseline, main & high
  * profiles.
  *
  * This structure holds information for \c seq_parameter_set_data() as
@@ -523,6 +523,19 @@ typedef struct _VAEncSliceParameterBufferH264 {
 #define VA_MB_PRED_AVAIL_LEFT             (1 << 6)
 /**@}*/
 
+/**
+ * \brief Macroblock parameter for H.264 encoding in baseline, main & high
+ * profiles.
+ *
+ * This structure holds per-macroblock information. The buffer must be
+ * allocated with as many elements (macroblocks) as necessary to fit
+ * the slice to be encoded. Besides, the per-macroblock records must
+ * be written in a strict raster order and with no gap. i.e. every
+ * macroblock, regardless of its type, shall have an entry.
+ */
+
+/**@}*/
+
 #ifdef __cplusplus
 }
 #endif