Update for <rust-lang/rust#23316>.

Author: Ms2ger

src/lib.rs

@@ -66,7 +66,7 @@ pub extern fn read_data(png_ptr: *mut ffi::png_struct, data: *mut u8, length: si
     }
 }
 
-pub fn load_png<P: AsPath + ?Sized>(path: &P) -> Result<Image,String> {
+pub fn load_png<P: AsPath>(path: P) -> Result<Image,String> {
     let mut reader = match File::open(path) {
         Ok(r) => r,
         Err(e) => return Err(format!("could not open file: {}", e.description())),
@@ -191,7 +191,7 @@ pub extern fn flush_data(png_ptr: *mut ffi::png_struct) {
     }
 }
 
-pub fn store_png<P: AsPath + ?Sized>(img: &mut Image, path: &P) -> Result<(),String> {
+pub fn store_png<P: AsPath>(img: &mut Image, path: P) -> Result<(),String> {
     let mut file = match File::create(path) {
         Ok(f) => f,
         Err(e) => return Err(format!("{}", e))