Ensure only the filtered environment variables are inherited from the OS

The recent change which modified inheritFromOS to use the intial
environment, rather than the current environment, introduced a bug such
that variables which had been cleaned from the environment where still set
in the data store.

This patch changes things such that a list of approved environment
variables is saved after the environment is cleaned and only the variables
in this list are inherited in inheritFromOS.

CC: James Limbouris <james.limbouris@gmail.com>
CC: Chris Larson <clarson@kergoth.com>
(Bitbake rev: cb6c07054e8baf94614713ec257c643b22266d75)

Signed-off-by: Joshua Lock <josh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/bin/bitbake-layers

@@ -31,9 +31,10 @@ def main(args):
     console.setFormatter(format)
     logger.addHandler(console)
 
+    initialenv = os.environ.copy()
     bb.utils.clean_environment()
 
-    cmds = Commands()
+    cmds = Commands(initialenv)
     if args:
         cmds.onecmd(' '.join(args))
     else:
@@ -42,9 +43,8 @@ def main(args):
 
 
 class Commands(cmd.Cmd):
-    def __init__(self):
+    def __init__(self, initialenv):
         cmd.Cmd.__init__(self)
-        initialenv = os.environ.copy()
         self.returncode = 0
         self.config = Config(parse_only=True)
         self.cooker = bb.cooker.BBCooker(self.config,