libvpx: Pull from upstream

source/libvpx/vp9/common/vp9_convolve.h

 /*
  *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #ifndef VP9_COMMON_CONVOLVE_H_
 #define VP9_COMMON_CONVOLVE_H_
 
 #include "./vpx_config.h"
 #include "vpx/vpx_integer.h"
 
+#define FILTER_BITS 7
+
 typedef void (*convolve_fn_t)(const uint8_t *src, ptrdiff_t src_stride,
                               uint8_t *dst, ptrdiff_t dst_stride,
                               const int16_t *filter_x, int x_step_q4,
                               const int16_t *filter_y, int y_step_q4,
                               int w, int h);
 
 struct subpix_fn_table {
   const int16_t (*filter_x)[8];
   const int16_t (*filter_y)[8];
 };
 
 #endif  // VP9_COMMON_CONVOLVE_H_