Fixes expose of staticmethod

Since 9358e59af80d9c5f88d5713ca7d1e648bfad1403, we cannot expose
staticmethod anymore because the pecan.util.getargspec is now looking
for the content of __closure__ that is None is this case.

This changes fixed that

Change-Id: Iabba8310cc58e155c6aeefc481e118de84c58734
Merge "Fixes expose of staticmethod"