Don't allow empty string as first argument of action.

Don't allow empty string as first argument of action.

For some reason, there was an extra empty argument at the beginning of these
cygwin rules. It looks like it was originally in rules and copy-pasted to
rules-dirname, so I assume just a typo in the first place.

This Exception was not raised when I ran "python build/gyp_chromium" on the Chromium code base.
Committed: https://code.google.com/p/gyp/source/detail?r=1233

[(unused - use chromium), 2012-02-23 01:55:19]

LGTM

Please land a gyp roll soon after landing.

https://chromiumcodereview.appspot.com/9451001/diff/1/pylib/gyp/input.py
File pylib/gyp/input.py (right):

https://chromiumcodereview.appspot.com/9451001/diff/1/pylib/gyp/input.py#newc...
pylib/gyp/input.py:2156: if action_command:
if action_command and not action-command[0]:
  raise...