[U-Boot] [PATCH 4/4] buildman: Show boards with warning with w+

[sjg at google.com]

At present we should boards with warnings in the same way as those with
errors. This is not ideal. Add a new 'warn' state and show these listed
in yellow to match the actual warning lines printing with -e.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

 tools/buildman/builder.py | 17 +++++++++---
 tools/buildman/test.py    | 56 ++++++++++++++++++++++++++++-----------
 2 files changed, 54 insertions(+), 19 deletions(-)

Applied to u-boot-dm/master, thanks!