[libpng16] Removed call to png_read_start_image() from the fuzzer. In libpng16

it is an error to call that along with png_read_update_info().

contrib/oss-fuzz/libpng_read_fuzzer.cc

@@ -171,8 +171,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
   png_read_update_info(png_handler.png_ptr, png_handler.info_ptr);
 
-  png_start_read_image(png_handler.png_ptr);
-
   png_handler.row_ptr = png_malloc(
       png_handler.png_ptr, png_get_rowbytes(png_handler.png_ptr,
                                             png_handler.info_ptr));