Instead of capturing the output of diff and printing it, let diff do its
own outputting and se the return code to decide what to do.
This also means that the conversion of stdout to UTF-8 is not necessary,
as the reason it was needed was for printing diffs of files with UTF-8
characters in them.
Signed-off-by: David Horstmann <david.horstmann@arm.com>
ce42cc24d1