Android420ToI420 - use ptrdiff_t for difference of u and v pointers

source/convert.cc

 /*
  *  Copyright 2011 The LibYuv 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.
  */
 
@@ skipping 1478 matching lines @@
                      int src_pixel_stride_uv,
                      uint8* dst_y,
                      int dst_stride_y,
                      uint8* dst_u,
                      int dst_stride_u,
                      uint8* dst_v,
                      int dst_stride_v,
                      int width,
                      int height) {
   int y;
-  const int vu_off = src_v - src_u;
+  const ptrdiff_t vu_off = src_v - src_u;
   int halfwidth = (width + 1) >> 1;
   int halfheight = (height + 1) >> 1;
   if (!src_u || !src_v || !dst_u || !dst_v || width <= 0 || height == 0) {
     return -1;
   }
   // Negative height means invert the image.
   if (height < 0) {
     height = -height;
     halfheight = (height + 1) >> 1;
     src_y = src_y + (height - 1) * src_stride_y;
@@ skipping 35 matching lines @@
     dst_u += dst_stride_u;
     dst_v += dst_stride_v;
   }
   return 0;
 }
 
 #ifdef __cplusplus
 }  // extern "C"
 }  // namespace libyuv
 #endif