Since we're going to have multiple hash algorithms to test, it makes
sense to share as much of the test code as possible. Convert the sha1
helper for the test-tool to be generic and move it out into its own
module. This will allow us to share most of this code with our NewHash
implementation.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>