[PATCH v2 09/28] buildman: Use an object to hold error lines

[sjg at google.com]

At present the string for each error line is created in _CalcErrorDelta()
and used to create the summary output. This is inflexible since all the
information (error/warning character, error line, list of boards with that
error line) is munged together in a string.

Create an object to hold this information and only convert it to a string
when printing the actual output.

Signed-off-by: Simon Glass <sjg at chromium.org>
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Changes in v2: None

 tools/buildman/builder.py | 69 +++++++++++++++++++++++++++++----------
 1 file changed, 52 insertions(+), 17 deletions(-)

Applied to u-boot-dm, thanks!