Ideally the result of the generator would conform to the code style, but
this would be difficult, especially with respect to the placement of line
breaks in long logical lines. So, to avoid surprises when checking the style
of generated files (which happens in releases and in long-time support
branches), systematically skip generated files.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>