PKCS#11 softtoken should use explicit_bzero
Review Request #1125 - Created July 6, 2018 and submitted
Update pkcs11 to use explicit_bzero(3C) and freezero(3C)
Ran the crypto test suite before and after building this code and saw identitical results.
The existing source had lots of cstyle issues, while this change doesn't add any problems, I bit the bullet and cleaned up the existing ones.