classes/buildhistory: add new output history collection class
Create a new build output history reporting class, using testlab.bbclass
from meta-oe as a base. This records information from images produced by
the build process in text files structured suitably for tracking within
a git repository, thus enabling monitoring of changes over time.
Build history collection can be enabled simply by adding the following
to your local.conf:
INHERIT += "buildhistory"
The output after a build can then be found in BUILDHISTORY_DIR (defaults to
TMPDIR/buildhistory). If you set up this directory as a git repository and
set BUILDHISTORY_COMMIT to "1" in local.conf, the build history data will
be committed on every build.
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>