Skip init on clone

The cloned buffer's content is not observable until written into, so
there is no need to keep it identical to the old buffer's content.

src/buffer/mod.rs

@@ -21,7 +21,6 @@ const NEG_INFINITY: &'static str = "-inf";
 /// let printed = buffer.format_finite(1.234);
 /// assert_eq!(printed, "1.234");
 /// ```
-#[derive(Copy, Clone)]
 pub struct Buffer {
     #[cfg(maybe_uninit)]
     bytes: [MaybeUninit<u8>; 24],
@@ -93,6 +92,15 @@ impl Buffer {
     }
 }
 
+impl Copy for Buffer {}
+
+impl Clone for Buffer {
+    #[inline]
+    fn clone(&self) -> Self {
+        Buffer::new()
+    }
+}
+
 impl Default for Buffer {
     #[inline]
     #[cfg_attr(feature = "no-panic", no_panic)]