[yocto] Patching bbclass file

[Marcelo Magallon]

On Tue, Oct 16, 2018 at 03:46:25PM +0100, Burton, Ross wrote:
>This is simply because you can't patch a bbclass.  You'll have to copy
>it into your layer with the modification, or work upstream to get a
>suitable change merged.

What I've done in this situation is add a new layer 
(poky-patches), add the modified foo.bbclass file there and when 
upgrading from one version of poky to the next, compare the old 
and new foo.bbclass files in poky. If they have changed, I do a 
three-way merge.

Marcelo