There are small systems which don't need OpenSSL or gcrypt.
Add libsha1 (http://github.com/dottedmag/libsha1) as an alternative
small SHA1 implementation.
Signed-off-by: Mikhail Gusarov <dottedmag@dottedmag.net>
Signed-off-by: Keith Packard <keithp@keithp.com>