tests: move mock blackbox extension into own file
Having all blackbox log testing in test-blackbox.t isn't scalable. Move
the mock blackbox extension into its own file so we can start to move
blackbox logging into other tests.
#!/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)