Use errno.EDEADLK instead of errno.EDEADLOCK

EDEADLOCK doesn't exist on Darwin, but EDEADLK does and is equivalent on Linux.

```
Bens-Mac:fig ben$ python
Python 2.7.2 (default, Oct 11 2012, 20:14:37) 
[GCC 4.2.1 Compatible Apple Clang 4.0 (tags/Apple/clang-418.0.60)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import errno
>>> errno.EDEADLOCK
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'EDEADLOCK'
>>> dir(errno)
['E2BIG', 'EACCES', 'EADDRINUSE', 'EADDRNOTAVAIL', 'EAFNOSUPPORT', 'EAGAIN', 'EALREADY', 'EAUTH', 'EBADARCH', 'EBADEXEC', 'EBADF', 'EBADMACHO', 'EBADMSG', 'EBADRPC', 'EBUSY', 'ECANCELED', 'ECHILD', 'ECONNABORTED', 'ECONNREFUSED', 'ECONNRESET', 'EDEADLK', 'EDESTADDRREQ', 'EDEVERR', 'EDOM', 'EDQUOT', 'EEXIST', 'EFAULT', 'EFBIG', 'EFTYPE', 'EHOSTDOWN', 'EHOSTUNREACH', 'EIDRM', 'EILSEQ', 'EINPROGRESS', 'EINTR', 'EINVAL', 'EIO', 'EISCONN', 'EISDIR', 'ELOOP', 'EMFILE', 'EMLINK', 'EMSGSIZE', 'EMULTIHOP', 'ENAMETOOLONG', 'ENEEDAUTH', 'ENETDOWN', 'ENETRESET', 'ENETUNREACH', 'ENFILE', 'ENOATTR', 'ENOBUFS', 'ENODATA', 'ENODEV', 'ENOENT', 'ENOEXEC', 'ENOLCK', 'ENOLINK', 'ENOMEM', 'ENOMSG', 'ENOPOLICY', 'ENOPROTOOPT', 'ENOSPC', 'ENOSR', 'ENOSTR', 'ENOSYS', 'ENOTBLK', 'ENOTCONN', 'ENOTDIR', 'ENOTEMPTY', 'ENOTRECOVERABLE', 'ENOTSOCK', 'ENOTSUP', 'ENOTTY', 'ENXIO', 'EOPNOTSUPP', 'EOVERFLOW', 'EOWNERDEAD', 'EPERM', 'EPFNOSUPPORT', 'EPIPE', 'EPROCLIM', 'EPROCUNAVAIL', 'EPROGMISMATCH', 'EPROGUNAVAIL', 'EPROTO', 'EPROTONOSUPPORT', 'EPROTOTYPE', 'EPWROFF', 'ERANGE', 'EREMOTE', 'EROFS', 'ERPCMISMATCH', 'ESHLIBVERS', 'ESHUTDOWN', 'ESOCKTNOSUPPORT', 'ESPIPE', 'ESRCH', 'ESTALE', 'ETIME', 'ETIMEDOUT', 'ETOOMANYREFS', 'ETXTBSY', 'EUSERS', 'EWOULDBLOCK', 'EXDEV', '__doc__', '__name__', '__package__', 'errorcode']

```

```
ben@computer ~/p/fig [master *]
± % docker run -t -i python python                                                 !2484
Python 3.4.1 (default, Jun 24 2014, 09:22:13)
[GCC 4.8.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import errno
>>> errno.EDEADLOCK
35
>>> errno.EDEADLK
35
>>>
```