[yocto] Adding 'build-id' to Build Image

[Leo Schwab]

We'd like to have the system images we build to contain a build id, or
at least a pile of information inside the image itself that lets us
identify which build is being run/tested.  Indeed, the information
'bitbake' kicks out just as it starts a build is exactly the sort of
thing we'd like sitting in a file in the image somewhere.

I turned on the 'buildhistory' feature in conf/local.conf which, among
other things, generates a 'build-id' file.  However, it doesn't place
it in the image, but in an entirely separate directory hierarchy.

Surely this sort of thing has been done before.  Is there an existing
recipe I can use, or will I have to cobble together a custom recipe
out of buildhistory_get_layers() or get_layers_branch_rev()?

Thanks,
Schwab