libvpx: Pull from upstream

source/libvpx/vp9/encoder/vp9_lookahead.c

 /*
  *  Copyright (c) 2011 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.
  */
 #include <assert.h>
@@ skipping 156 matching lines @@
   }
   return buf;
 }
 
 
 struct lookahead_entry *
 vp9_lookahead_peek(struct lookahead_ctx *ctx,
                    int                   index) {
   struct lookahead_entry *buf = NULL;
 
-  assert(index < ctx->max_sz);
+  assert(index < (int)ctx->max_sz);
   if (index < (int)ctx->sz) {
     index += ctx->read_idx;
     if (index >= (int)ctx->max_sz)
       index -= ctx->max_sz;
     buf = ctx->buf + index;
   }
   return buf;
 }
 
 
 unsigned int
 vp9_lookahead_depth(struct lookahead_ctx *ctx) {
   return ctx->sz;
 }