This was brought in in 2016 and a number of changes have been made since
then. There does not seem to be much change in functionality, but it is
a good idea to update from time to time.
Bring in the latest version:
5736b15 ("re-add perlin noise again")
Add a few necessary functions, with dummies in some cases. Update the tests
as there are subtle changes in rendering, perhaps not for the better.
Signed-off-by: Simon Glass <sjg@chromium.org>
04f3dcd503