cups/hash.c: Put support for MacOS/Win SSL libs back

cups/hash.c: Put support for MacOS/Win SSL libs back

- I mustn't remove their support in patch release - this should happen in 2.5 only.
- I have put back support for several hashes as well - they should be removed in 2.5.
- restrict usage of second block hashing only if OpenSSL/LibreSSL/GnuTLS is available (since IMO I found its implementation useless for SSL libs, which will be removed in 2.5)

This removes hard dependency on OpenSSL/LibreSSL or GnuTLS in 2.4.x, which will happen in 2.5.