Revert "Fix AVChannelLayout::describe"

This reverts commit 75f7a29.

src/avutil/channel_layout.rs

@@ -99,26 +99,22 @@ impl AVChannelLayout {
     /// channel layout, except for opaque pointers.
     pub fn describe(&self) -> Result<CString> {
         const BUF_SIZE: usize = 32;
-        let mut buf = vec![0u8; BUF_SIZE + 1];
-
-        // Note: len doesn't include the trailing zero
-        //
+        let mut buf = vec![0u8; BUF_SIZE];
         // # Safety: after upgrading len is assumed to be positive.
         let len = unsafe {
             ffi::av_channel_layout_describe(self.as_ptr(), buf.as_mut_ptr() as *mut i8, BUF_SIZE)
         }
         .upgrade()? as usize;
-
         let len = if len > BUF_SIZE {
-            buf.resize(len + 1, 0);
+            buf.resize(len, 0);
             unsafe {
                 ffi::av_channel_layout_describe(self.as_ptr(), buf.as_mut_ptr() as *mut i8, len)
             }
             .upgrade()? as usize
         } else {
             len
         };
-        Ok(CString::new(&buf[..len + 1]).unwrap())
+        Ok(CString::new(&buf[..len]).unwrap())
     }
 
     /// Get the channel with the given index in a channel layout.