Code: get_control(png_const_structrp png_ptr)
{

    /* This just returns the (file*).  The chunk and idat control structures
     * don't always exist.
     */
   struct control *control = png_voidcast(struct control*,
       png_get_error_ptr(png_ptr));
    return &control->file;
 }

Commit Message: DO NOT MERGE Update libpng to 1.6.20

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

CWE ID: 
get_control(png_const_structrp png_ptr)
{

    /* This just returns the (file*).  The chunk and idat control structures
     * don't always exist.
     */
   struct control *control = voidcast(struct control*,
       png_get_error_ptr(png_ptr));
    return &control->file;
 }
