crypto: lib - move lib/sha1.c into lib/crypto/

SHA-1 is a crypto algorithm (or at least was intended to be -- it's not
considered secure anymore), so move it out of the top-level library
directory and into lib/crypto/.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>