UnicodeDecode error when running lsmod_info script with "C" locale

This was observed when running Checkbox as root, such that LANG and LANGUAGE are set to "C".

Steps to reproduce:

$ LANG=C LANGUAGE=C /usr/share/checkbox/scripts/lsmod_info

Expected result:
- List of modules and versions

Actual result:
- When hitting "drm" module, which has a non-ASCII character (José), this trace appears:

dm_raid45: 3.2.0-30-generic
dm_region_hash: 3.2.0-30-generic
Traceback (most recent call last):
  File "/usr/share/checkbox/scripts/lsmod_info", line 32, in <module>
    sys.exit(main())
  File "/usr/share/checkbox/scripts/lsmod_info", line 18, in main
    stream, err = process.communicate()
  File "/usr/lib/python3.2/subprocess.py", line 819, in communicate
    return self._communicate(input)
  File "/usr/lib/python3.2/subprocess.py", line 1440, in _communicate
    self.stdout.encoding)
  File "/usr/lib/python3.2/subprocess.py", line 759, in _translate_newlines
    return data.decode(encoding)
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 207: ordinal not in range(128)

If modinfo will always output utf-8, one thing to do would be forcing string handling to use utf-8 always, regardless of autodetected charset based on locale.