Convert pbkdf2_*.h into proper functions and add *_ZEROS logic where possible

Several issues here.

1. create a proper .h file that defines the available functions
2. create a .c file that has all these functions as globals.
3. NOTE, there may be several versions for some hashes:
   i.e. pbkdf2_hmac_sha256, pbkdf1_hmac_sha256, pbkdf2_hmac_sha256_efs would be available in the sha256 file.
   These extra functions probably should be able to be done with #include of the code again, with a couple #defines.
4. modify any external .c files including this, where the function name would change. (such as pbkdf1, or the _efs variants)
5. add any 'missing' pbkdf1_* functions to the hashes.
6. Add any additional crypts (such as BF)
7. add *ZEROS logic where we can. The *_ZEROS logic would be in the inner loop of the pbkdf2 run, where we KNOW a large part of the input data is null bytes.

Start by inventorying the existing pbkdf2_*.h files, their related hash files, and external .c files that include or call them. Map the existing PBKDF1, PBKDF2, _efs, and available crypt implementations before deciding the shared header and source boundaries. Done means global functions and declarations are organized, missing variants and applicable *_ZEROS paths are covered, and callers use the renamed functions.