DO NOT MERGE Update libpng to 1.6.20

BUG:23265085
Change-Id: I85199805636d771f3597b691b63bc0bf46084833
(cherry picked from commit bbe98b40cda082024b669fa508931042eed18f82)

png_row_in_interlace_pass(png_uint_32 y, int pass)
{
 /* Is row 'y' in pass 'pass'? */
 int x;
   y &= 7;
 ++pass;
 for (x=0; x<8; ++x) if (adam7[y][x] == pass)
 return 1;

 return 0;
}

png_row_in_interlace_pass(png_uint_32 y, int pass)
{
 /* Is row 'y' in pass 'pass'? */
 int x;
   y &= 7;
 ++pass;
 for (x=0; x<8; ++x) if (adam7[y][x] == pass)
 return 1;

 return 0;
}
