New function to lookup digests by NID in module.

Minor optimisation: if supplied hash is NULL to FIPS RSA functions and
we are using PKCS padding get digest NID from otherwise unused saltlen
parameter instead.

instead of using regular OpenSSL API names.

a context.

OpenSSL malloc dependencies.

to EVP any more.

Move locking #define into fips.h.

Set FIPS locking callbacks at same time as OpenSSL locking callbacks.

Initial FIPS 140-2 code ported to HEAD. Doesn't even compile yet, may have
missing files, extraneous files and other nastiness.

In other words: it's experimental ATM, OK?