Revert "Revert "CRYPTO: Suppress warning Wstringop-truncation""
    
    This reverts commit bb20d5160faed5e0076887ac4a83e550be15a8b2.
    
    The patch introduced compile time warning
    src/util/crypto/libcrypto/crypto_sha512crypt.c:280:10: error: 'stpncpy'
        output truncated before terminating nul copying 3 bytes from a string
        of the same length [-Werror=stringop-truncation]
         cp = stpncpy(buffer, sha512_salt_prefix, SALT_PREF_SIZE);
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    
    Merges: https://pagure.io/SSSD/sssd/pull-request/3792
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>