Fix compilation errors and warnings

Author: newpavlov

aead/src/dyn_aead.rs

@@ -1,6 +1,6 @@
 use inout::{InOutBuf, InOutBufReserved};
 
-use crate::{Aead, Error, Payload, Result};
+use crate::{Aead, Error, Result};
 
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
@@ -141,14 +141,14 @@ impl<T: Aead> DynAead for T {
     #[cfg(feature = "alloc")]
     fn encrypt_to_vec(&self, nonce: &[u8], aad: &[u8], msg: &[u8]) -> Result<Vec<u8>> {
         let nonce = nonce.try_into().map_err(|_| Error)?;
-        let payload = Payload { aad, msg };
+        let payload = crate::Payload { aad, msg };
         Aead::encrypt_to_vec(self, nonce, payload)
     }
 
     #[cfg(feature = "alloc")]
     fn decrypt_to_vec(&self, nonce: &[u8], aad: &[u8], msg: &[u8]) -> Result<Vec<u8>> {
         let nonce = nonce.try_into().map_err(|_| Error)?;
-        let payload = Payload { aad, msg };
+        let payload = crate::Payload { aad, msg };
         Aead::decrypt_to_vec(self, nonce, payload)
     }
 }

aead/src/lib.rs

@@ -339,6 +339,7 @@ pub trait Aead {
     /// AES-GCM-SIV, ChaCha20Poly1305). [`Aead`] implementations which do not
     /// use a postfix tag will need to override this to correctly parse the
     /// ciphertext message.
+    #[cfg(feature = "alloc")]
     #[inline]
     fn decrypt_to_vec<'msg, 'aad>(
         &self,