enable interlace transform when reading png (#823)

src/gd_png.c

@@ -415,6 +415,11 @@ BGD_DECLARE(gdImagePtr) gdImageCreateFromPngCtx (gdIOCtx * infile)
 		goto error;
 	}
 
+	/* enable the interlace transform if supported */
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+	(void)png_set_interlace_handling(png_ptr);
+#endif
+
 	png_read_update_info (png_ptr, info_ptr);
 
 	/* allocate space for the PNG image data */