Fix minor clippy lints

src/util/channel_layout/iter.rs

@@ -15,6 +15,12 @@ impl ChannelLayoutIter {
     }
 }
 
+impl Default for ChannelLayoutIter {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl Iterator for ChannelLayoutIter {
     type Item = ChannelLayout<'static>;
 

src/util/channel_layout/mask.rs

@@ -2,7 +2,7 @@ use crate::ffi::*;
 use libc::c_ulonglong;
 
 bitflags! {
-    #[derive(Eq, PartialEq, Copy, Clone)]
+    #[derive(Eq, PartialEq, Copy, Clone, Debug)]
     pub struct ChannelLayoutMask: c_ulonglong {
         const FRONT_LEFT            = AV_CH_FRONT_LEFT;
         const FRONT_RIGHT           = AV_CH_FRONT_RIGHT;