scrypt: commit packaging improvements

The changes brought by this commit should have been part of the
previous commit, but were not due to a mistake. This commit implements
the following changes to the scrypt package:

   - move from "Libraries -> Crypto" to "System tools", since it only
     installs one binary, scrypt, and no library.
   - bump from 1.1.6 to 1.2.0
   - add comment in the .hash file explaining where the hash is coming
     from.
   - add missing dependency on OpenSSL
   - use BSD-2c as the license code, instead of BSD2
   - use 'main.c' as the license file.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>