update license of compat and crypto

- change license to be just MIT for all files in compat and crypto
- also add missing header end comments
- ensure default header include style

src/crypto/sha2.cpp

@@ -1,5 +1,5 @@
 // Copyright (c) 2014 The Bitcoin developers
-// Distributed under the MIT/X11 software license, see the accompanying
+// Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "crypto/sha2.h"