f4da46b libcrypto: Check right value of CRYPTO_memcmp

Authored and Committed by lslebodn 7 years ago
    libcrypto: Check right value of CRYPTO_memcmp
    
    sss_decrypt failed even though should pass because
    we were checking wrong value of CRYPTO_memcmp.
    Nobody noticed that because there was not a unit test :-)
    
    Reviewed-by: Christian Heimes <cheimes@redhat.com>
    (cherry picked from commit 0c2be9700d3b54db33c1a3dd5d230b34bfaceb50)