tests/readlink.py

tests: run check-code with warnings and maintain a whitelist

check-code has fine warning checks, but they are a bit noisy and nobody used
them.

Now the warnings will be run in the test suite, where a list of accepted
warnings will be maintained.

Those who introduce or touch a line with a warning will now have to update the
whitelist ... or fix the warning.

#!/usr/bin/env python

import errno, os, sys

for f in sys.argv[1:]:
    try:
        print f, '->', os.readlink(f)
    except OSError, err:
        if err.errno != errno.EINVAL:
            raise
        print f, 'not a symlink'

sys.exit(0)