bitbake: BBHandler/cooker: Implement recipe and global classes

We have some confusion for users since some classes are meant to work
in the configuration space (or "globally") and some are meant to be
selected by recipes individually.

The cleanest way I could find to clarify this is to create "classes-global"
and "classes-recipe" directories which contain the approproate classes and
have bitbake switch scope between them at the appropriate point during
parsing. The existing "classes" directory is always searched as a fallback.

Once a class is moved to a specific directory, it will no longer be found
in the incorrect context. A good example from OE is that

INHERIT += "testimage"

will no longer work but

IMAGE_CLASSES += "testimage"

will, which makes the global scope cleaner by only including it where it
is useful and intended to be used (images).

(Bitbake rev: f33ce7e742f46635658c400b82558cf822690b5e)

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

bitbake/lib/bb/tests/parse.py

@@ -164,6 +164,7 @@ python () {
     # become unset/disappear.
     #
     def test_parse_classextend_contamination(self):
+        self.d.setVar("__bbclasstype", "recipe")
         cls = self.parsehelper(self.classextend_bbclass, suffix=".bbclass")
         #clsname = os.path.basename(cls.name).replace(".bbclass", "")
         self.classextend = self.classextend.replace("###CLASS###", cls.name)