classes/buildhistory: ensure that git user email and name are set
The git user.email and user.name settings must be set or the commit to
the buildhistory repo (when BUILDHISTORY_COMMIT is set to "1") will
fail. If the user hasn't set these, set some dummy values since the
actual value is unlikely to be particularly useful and it's far worse
for the commit not to be done leaving the repository in a partially set
up state.
Prompted by [YOCTO #6973].
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
