devtool/friends: Use LAYERSERIES_CORENAMES when generating LAYERSERIES_COMPAT entries

It seems some layers want to subvert the intent of LAYERSERIES_COMPAT
so bitbake is going to have to become stricter about the values there.
To work with this, use LAYERSERIES_CORENAMES to generate the entries in
LAYERSERIES_COMPAT instead of the current magic LAYERSERIES_COMPAT_core
value which may not continue to work.

The downside to this is when migating between releases, people would
need to update devtool workspace layer.conf files. I guess you could
argue this is a feature!

(From OE-Core rev: 96ff9baa8ead57504f40f362ed3a4aaa776d1b58)

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

meta/classes-recipe/populate_sdk_ext.bbclass

@@ -255,7 +255,7 @@ python copy_buildsystem () {
     bbpath = d.getVar('BBPATH')
     env = os.environ.copy()
     env['PYTHONDONTWRITEBYTECODE'] = '1'
-    bb.process.run(['devtool', '--bbpath', bbpath, '--basepath', baseoutpath, 'create-workspace', '--create-only', os.path.join(baseoutpath, 'workspace')], env=env)
+    bb.process.run(['devtool', '--bbpath', bbpath, '--basepath', baseoutpath, 'create-workspace', '--layerseries', d.getVar("LAYERSERIES_CORENAMES"), '--create-only', os.path.join(baseoutpath, 'workspace')], env=env)
 
     # Create bblayers.conf
     bb.utils.mkdirhier(baseoutpath + '/conf')
@@ -498,7 +498,6 @@ python copy_buildsystem () {
     else:
         tasklistfn = None
 
-
     cachedir = os.path.join(baseoutpath, 'cache')
     bb.utils.mkdirhier(cachedir)
     bb.parse.siggen.copy_unitaskhashes(cachedir)