update.sh: Kept LF at EOF.

Signed-off-by: FrankHB <frankhb1989@gmail.com>
update.sh: Allowed current working directory out of tree.

Signed-off-by: FrankHB <frankhb1989@gmail.com>
update.sh: Hash "python3" to prevent overwriting output when python3 executable not found.

Signed-off-by: FrankHB <frankhb1989@gmail.com>