In Crypto++ v6, the `byte` typedef has been moved from the global namespace to the CryptoPP:: namespace. To make Scylla code compile with both old and new versions, bring the namespace in so that the code works regardless of the scope of `byte` definition. Fixes #3252 Signed-off-by: Vladimir Krivopalov <vladimir@scylladb.com> Message-Id: <60e7bfe868b778b1c9bbe15d7247db64b61bd406.1520272198.git.vladimir@scylladb.com>