Make no-float policy explicit
Make no-float policy explicit

We don't want floating types for various reasons, e.g.,
 - Their representation and often their behavior is implementation-defined.
 - Many targets don't support them.
afk11/secp256k1,bitcoin/secp256k1,evoskuil/secp256k1,evoskuil/secp256k1,bitcoin/secp256k1,bitcoin/secp256k1,bitcoin/secp256k1,bitcoin-core/secp256k1,evoskuil/secp256k1,afk11/secp256k1,ElementsProject/secp256k1-zkp,peterdettman/secp256k1,afk11/secp256k1,afk11/secp256k1,evoskuil/secp256k1,bitcoin-core/secp256k1,peterdettman/secp256k1,evoskuil/secp256k1,bitcoin/secp256k1,ElementsProject/secp256k1-zkp,afk11/secp256k1