Add a new/extend x509 perf test

[npajkovsky]

It has been found during testing that our perftool test is not sufficient. Test calls only one function X509_STORE_CTX_get1_issuer with certificate that is always not found and miss the cache. We should have more realistic test cases such as adding certificates while reading the cache and therefore generate more lock contentions.

Functions that add CRL and certs are:

int X509_STORE_add_cert(X509_STORE *xs, X509 *x)
int X509_STORE_add_crl(X509_STORE *xs, X509_CRL *x)

Construct the test in a way that you can specify how many threads are writing, and how fast.