asyncio.unix_events: Move import statement to match tulip code

Lib/asyncio/unix_events.py

 """Selector event loop for Unix with signal handling."""
 
 import errno
-import fcntl
 import os
 import signal
 import socket
@@ -263,6 +262,8 @@ if hasattr(os, 'set_blocking'):
     def _set_nonblocking(fd):
         os.set_blocking(fd, False)
 else:
+    import fcntl
+
     def _set_nonblocking(fd):
         flags = fcntl.fcntl(fd, fcntl.F_GETFL)
         flags = flags | os.O_NONBLOCK