Fix integer issues in a way that caters for both 32-bit and 64-bit.

third_party/libpng/pngrutil.c

 
 /* pngrutil.c - utilities to read a PNG file
  *
  * Last changed in libpng 1.2.45 [July 7, 2011]
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
@@ skipping 229 matching lines @@
       ret = inflate(&png_ptr->zstream, Z_NO_FLUSH);
       avail = png_ptr->zbuf_size - png_ptr->zstream.avail_out;
 
       /* First copy/count any new output - but only if we didn't
        * get an error code.
        */
       if ((ret == Z_OK || ret == Z_STREAM_END) && avail > 0)
       {
          if (output != 0 && output_size > count)
          {
-            int copy = output_size - count;
-            if (avail < copy) copy = avail;
+            png_size_t copy = output_size - count;
+            if ((png_size_t) avail < copy) copy = (png_size_t) avail;
             png_memcpy(output + count, png_ptr->zbuf, copy);
          }
          count += avail;
       }
 
       if (ret == Z_OK)
          continue;
 
       /* Termination conditions - always reset the zstream, it
        * must be left in inflateInit state.
@@ skipping 3126 matching lines @@
    png_debug1(3, "height = %lu,", png_ptr->height);
    png_debug1(3, "iwidth = %lu,", png_ptr->iwidth);
    png_debug1(3, "num_rows = %lu,", png_ptr->num_rows);
    png_debug1(3, "rowbytes = %lu,", png_ptr->rowbytes);
    png_debug1(3, "irowbytes = %lu",
        PNG_ROWBYTES(png_ptr->pixel_depth, png_ptr->iwidth) + 1);
 
    png_ptr->flags |= PNG_FLAG_ROW_INIT;
 }
 #endif /* PNG_READ_SUPPORTED */