libselinux: Replace selabel_digest hash function

This replaces the openssl library with SHA1 hash functions
extracted from [1] as this is a public domain implementation.

util/selabel_digest -v option still compares the result with
the openssl command "openssl dgst -sha1 -hex .." for validation.

[1] https://github.com/WaterJuice/CryptLib

Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
6 files changed