recipetool: create: fix failure handling included dicts

If a setup dict in a python setup.py file pulled in the contents of
another dict (e.g.  **otherdict), then we got an error when mapping
the keys because the key is None in that case. Skip those keys to avoid
the error (we pick up the values directly in any case).

A quick reproducer for this issue:

recipetool create https://files.pythonhosted.org/packages/source/p/pyqtgraph/pyqtgraph-0.10.0.tar.gz

(From OE-Core rev: ae62a9953e219df5147ed4a5ae3f4163d51cff28)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/recipetool/create_buildsys_python.py

@@ -356,6 +356,8 @@ class PythonRecipeHandler(RecipeHandler):
         # Naive mapping of setup() arguments to PKG-INFO field names
         for d in [info, non_literals]:
             for key, value in list(d.items()):
+                if key is None:
+                    continue
                 new_key = _map(key)
                 if new_key != key:
                     del d[key]