This adds a ClassRegistry utility metaclass, as maintaining a class registry
is a fairly common thing to do.
(From OE-Core rev: 6a46c375bea03b145bea41ec29ae2fd4d3cd9db6)
Signed-off-by: Chris Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Chris Larson