[libpng16] Check for info_ptr == NULL early in png_read_end() so we don't need

to run all the png_handle_*() and depend on them to return if info_ptr == NULL.
This improves the performance of png_read_end(png_ptr, NULL) and makes
it more robust against future programming errors.

pngrutil.c

@@ -1436,7 +1436,7 @@ png_handle_iCCP(png_structrp png_ptr, png_inforp info_ptr, png_uint_32 length)
                               (sizeof local_buffer), &length,
                               profile + (sizeof profile_header), &size, 0);
 
-                           /* Still expect a a buffer error because we expect
+                           /* Still expect a buffer error because we expect
                             * there to be some tag data!
                             */
                            if (size == 0)