build: Always run checkapi when building system image

This should significantly reduce the number of quail stars given out.

This only applies when building the system image.  Packages may still
be built and tested individually without any impact.

If you like to live dangerously, set I_WANT_A_QUAIL_STAR in your
environment.

Change-Id: I3da6646f022f2e967ebe2c3dd9ed616fab7991fe

Add WITHOUT_CHECK_API guard around checkapi

* Granted we should never not check the API, the flag was added
  so we need to account for it

Change-Id: Iae58ab6484c5c72904cae30e74f5ea1e89a86618
Signed-off-by: Brandon McAnsh <brandon.mcansh@gmail.com>