Code: test_standard(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
    int bdlo, int PNG_CONST bdhi)
 {
    for (; bdlo <= bdhi; ++bdlo)
    {
 int interlace_type;

 for (interlace_type = PNG_INTERLACE_NONE;

            interlace_type < INTERLACE_LAST; ++interlace_type)
       {
          standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
            interlace_type, 0, 0, 0), 0/*do_interlace*/, pm->use_update_info);
 
          if (fail(pm))
             return 0;
 }
 }

 return 1; /* keep going */
}

Commit Message: DO NOT MERGE Update libpng to 1.6.20

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

CWE ID: 
test_standard(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
test_standard(png_modifier* const pm, png_byte const colour_type,
    int bdlo, int const bdhi)
 {
    for (; bdlo <= bdhi; ++bdlo)
    {
 int interlace_type;

 for (interlace_type = PNG_INTERLACE_NONE;

            interlace_type < INTERLACE_LAST; ++interlace_type)
       {
          standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
            interlace_type, 0, 0, 0), do_read_interlace, pm->use_update_info);
 
          if (fail(pm))
             return 0;
 }
 }

 return 1; /* keep going */
}
