Add sm4 encryption (#295)

[jiayang-zheng]

Origin PR #295

[Connor1996]

LGTM

[ethercflow]

Hi @jiayang-zheng , I compiled under Centos 8 stream, met a compile problem:

encryption/encryption.cc: In function 'rocksdb::Status rocksdb::encryption::NewAESCTRCipherStream(rocksdb::encryption::EncryptionMethod, const string&, const string&, std::unique_ptr<rocksdb::encryption::AESCTRCipherStream>*)':
encryption/encryption.cc:224:16: error: 'EVP_sm4_ctr' was not declared in this scope
       cipher = EVP_sm4_ctr();
                ^~~~~~~~~~~
encryption/encryption.cc:224:16: note: suggested alternative: 'NID_sm4_ctr'
       cipher = EVP_sm4_ctr();
                ^~~~~~~~~~~
                NID_sm4_ctr

The openssl and openssl-level have been installed, with version is 1.1.1k.

Would you please to see why?

[jiayang-zheng]

The yum install openssl 1.1.1k should be with the OPENSSL_NO_SM4 flag set.

# ifndef OPENSSL_NO_SM4
const EVP_CIPHER *EVP_sm4_ecb(void);
const EVP_CIPHER *EVP_sm4_cbc(void);
const EVP_CIPHER *EVP_sm4_cfb128(void);
#  define EVP_sm4_cfb EVP_sm4_cfb128
const EVP_CIPHER *EVP_sm4_ofb(void);
const EVP_CIPHER *EVP_sm4_ctr(void);
# endif

Fixed this issue in PR #302 #303
Thanks. @ethercflow