bitbake: cookerdata: Issue warning if layer doesn't set LAYERSERIES_COMPAT_x

We'd like layers to set this variable so that we know which layers are compatible
with which others, even if the branch is a generic un-updated "master" branch.

Start printing a warning to highlight this issue.

(Bitbake rev: cca81e33b58c390dcf5cc3a31555a43b79177166)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/cookerdata.py

@@ -396,6 +396,8 @@ class CookerDataBuilder(object):
                 if compat and not (compat & layerseries):
                     bb.fatal("Layer %s is not compatible with the core layer which only supports these series: %s (layer is compatible with %s)"
                               % (c, " ".join(layerseries), " ".join(compat)))
+                elif not compat and not data.getVar("BB_WORKERCONTEXT"):
+                    bb.warn("Layer %s should set LAYERSERIES_COMPAT_%s in its conf/layer.conf file to list the core layer names it is compatible with." % (c, c))
 
         if not data.getVar("BBPATH"):
             msg = "The BBPATH variable is not set"