Make hostwatch locale-independent (#379)

* Make hostwatch locale-independent

See #377: hostwatch used to call netstat and parse the result,
without setting the locale.
The problem is converting the binary output to a unicode string,
as the locale may be utf-8, latin-1, or literally anything.
Setting the locale to C avoids this issue, as netstat's source
strings to not use non-ASCII characters.

* Break line, check all other invocations

sshuttle/client.py

@@ -220,6 +220,7 @@ class FirewallClient:
                 if argv[0] == 'su':
                     sys.stderr.write('[local su] ')
                 self.p = ssubprocess.Popen(argv, stdout=s1, preexec_fn=setup)
+                # No env: Talking to `FirewallClient.start`, which has no i18n.
                 e = None
                 break
             except OSError as e: