bitbake: bitbake: Convert to python 3

Various misc changes to convert bitbake to python3 which don't warrant
separation into separate commits.

(Bitbake rev: d0f904d407f57998419bd9c305ce53e5eaa36b24)

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

bitbake/lib/bb/event.py

@@ -24,10 +24,7 @@ BitBake build tools.
 
 import os, sys
 import warnings
-try:
-    import cPickle as pickle
-except ImportError:
-    import pickle
+import pickle
 import logging
 import atexit
 import traceback
@@ -107,7 +104,7 @@ def fire_class_handlers(event, d):
 
     eid = str(event.__class__)[8:-2]
     evt_hmap = _event_handler_map.get(eid, {})
-    for name, handler in _handlers.iteritems():
+    for name, handler in list(_handlers.items()):
         if name in _catchall_handlers or name in evt_hmap:
             if _eventfilter:
                 if not _eventfilter(name, handler, event, d):
@@ -192,7 +189,7 @@ def register(name, handler, mask=None, filename=None, lineno=None):
 
     if handler is not None:
         # handle string containing python code
-        if isinstance(handler, basestring):
+        if isinstance(handler, str):
             tmp = "def %s(e):\n%s" % (name, handler)
             try:
                 code = bb.methodpool.compile_cache(tmp)