toaster: buildinfohelper Detect command line builds

toaster: buildinfohelper Detect command line builds

When we're building using toaster as just a listener to bitbake
(analysis mode) we need to handle the case where the toaster configuration data
isn't present so we don't need to try and update the existing information.

Signed-off-by: Michael Wood <michael.g.wood@intel.com>
Signed-off-by: Elliot Smith <elliot.smith@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>