bitcoin: Use no_std attribute

As we do for other crates; default to `no_std`.

bitcoin/src/lib.rs

@@ -28,7 +28,7 @@
 //!                            achieve the same without this feature but it could
 //!                            happen the implementations diverge one day.
 
-#![cfg_attr(all(not(feature = "std"), not(test)), no_std)]
+#![no_std]
 
 // Experimental features we need.
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
@@ -57,6 +57,9 @@ extern crate test;
 #[macro_use]
 extern crate alloc;
 
+#[cfg(feature = "std")]
+extern crate std;
+
 #[cfg(feature = "base64")]
 /// Encodes and decodes base64 as bytes or utf8.
 pub extern crate base64;

bitcoin/src/p2p/address.rs

@@ -13,6 +13,7 @@ use io::{BufRead, Read, Write};
 
 use crate::consensus::encode::{self, Decodable, Encodable, ReadExt, VarInt, WriteExt};
 use crate::p2p::ServiceFlags;
+use crate::prelude::*;
 
 /// A message which can be sent on the Bitcoin network
 #[derive(Clone, PartialEq, Eq, Hash)]

bitcoin/src/p2p/message_blockdata.rs

@@ -13,6 +13,7 @@ use crate::blockdata::block::BlockHash;
 use crate::blockdata::transaction::{Txid, Wtxid};
 use crate::consensus::encode::{self, Decodable, Encodable};
 use crate::internal_macros::impl_consensus_encoding;
+use crate::prelude::*;
 use crate::p2p;
 
 /// An inventory item.

bitcoin/src/p2p/message_bloom.rs

@@ -9,6 +9,7 @@ use io::{BufRead, Write};
 
 use crate::consensus::{encode, Decodable, Encodable, ReadExt};
 use crate::internal_macros::impl_consensus_encoding;
+use crate::prelude::*;
 
 /// `filterload` message sets the current bloom filter
 #[derive(Clone, PartialEq, Eq, Debug)]

bitcoin/src/p2p/message_filter.rs

@@ -8,6 +8,7 @@
 use crate::bip158::{FilterHash, FilterHeader};
 use crate::blockdata::block::BlockHash;
 use crate::internal_macros::impl_consensus_encoding;
+use crate::prelude::*;
 
 /// getcfilters message
 #[derive(PartialEq, Eq, Clone, Debug)]