NTLM: set a fake entropy for debug builds with CURL_ENTROPY set

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