Count/report hashes removed by --salts or --cost options

[magnumripper]

Closes #5699

[magnumripper]

Tested with --cost, --salts, none or both, with or without some hashes cracked.

[magnumripper]

Example output:

$ ../run/john -v:3 all_tests.in -form:sha512crypt -mask:a -cost=5000 --salts=-2
Loaded 33 password hashes with 15 different salts (2.2x same-salt boost) (sha512crypt, crypt(3) $6$ [SHA512 256/256 AVX2 4x])
Removed 20 password hashes due to --salts
Removed 1 password hash due to --cost
Cracked 2 password hashes (are in ../run/john.pot), use "--show"
Remaining 10 password hashes with 10 different salts
Cost 1 (iteration count) is 5000 for all remaining hashes

I could easily add how many salts each of the filter options removed, but I think it's overkill?

[solardiz]

I only skimmed. I think you also need to update the comment in loader.h on the return value of ldr_fix_database.

Other than that, this is good stuff, but it'd take a long while until I get around to reviewing this for real. So maybe just fix the comment and merge, and we'll rely on your own testing for now.