To force each backend implementation to really attempt to provide proper
random. If a proper random function is missing, then we can explicitly
make use of the default one we use when TLS support is missing.
This commit makes sure it works for darwinssl, gnutls, nss and openssl.
Curl_rand() will return a dummy and repatable random value for this
case. Makes it possible to write test cases that verify output.
Also, fake timestamp with CURL_FORCETIME set.
Only when built debug enabled of course.
Curl_ssl_random() was not used anymore so it has been
removed. Curl_rand() is enough.
create_digest_md5_message: generate base64 instead of hex string
curl_sasl: also fix memory leaks in some OOM situations
