[Buildroot] Trouble building the manual

[Sagaert Johan]

Hi 

Building the manual seems to be broken.
 
# make manual-pdf
>>>   Updating the manual lists...
Traceback (most recent call last):
  File "/home/buildroot12git/support/scripts/gen-manual-lists.py", line 41, in <module>
    from argparse import ArgumentParser
ImportError: No module named argparse
make: *** [manual-update-lists] Error 1

Sagaert Johan