unix: map ENODEV to UV_ENODEV

produces better error message from test-dgram-multicast-multi-process
when run w/o network.

before:

=== release test-dgram-multicast-multi-process ===
Path: simple/test-dgram-multicast-multi-process
dgram.js:287
    throw new errnoException(errno, 'addMembership');
          ^
Error: addMembership Unknown system errno 19
    at new errnoException (dgram.js:356:11)
    at Socket.addMembership (dgram.js:287:11)
    at Object.<anonymous> (/home/roman/wc/node/test/simple/test-dgram-multicast-multi-process.js:224:16)
    at Module._compile (module.js:449:26)
    at Object.Module._extensions..js (module.js:467:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.runMain (module.js:487:10)
    at process.startup.processNextTick.process._tickCallback (node.js:244:9)
[PARENT] Worker 9223 died. 1 dead of 3

dgram.js:287
    throw new errnoException(errno, 'addMembership');
          ^
Error: addMembership Unknown system errno 19
    at new errnoException (dgram.js:356:11)
    at Socket.addMembership (dgram.js:287:11)
    at Object.<anonymous> (/home/roman/wc/node/test/simple/test-dgram-multicast-multi-process.js:224:16)
    at Module._compile (module.js:449:26)
    at Object.Module._extensions..js (module.js:467:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.runMain (module.js:487:10)
    at process.startup.processNextTick.process._tickCallback (node.js:244:9)

[PARENT] sent 'First message to send' to 224.0.0.114:12346
dgram.js:287
[PARENT] sent 'Second message to send' to 224.0.0.114:12346
    throw new errnoException(errno, 'addMembership');
[PARENT] sent 'Third message to send' to 224.0.0.114:12346
          ^
[PARENT] sendSocket closed
[PARENT] Worker 9224 died. 2 dead of 3
Error: addMembership Unknown system errno 19
    at new errnoException (dgram.js:356:11)
    at Socket.addMembership (dgram.js:287:11)
    at Object.<anonymous> (/home/roman/wc/node/test/simple/test-dgram-multicast-multi-process.js:224:16)
    at Module._compile (module.js:449:26)
    at Object.Module._extensions..js (module.js:467:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.runMain (module.js:487:10)
    at process.startup.processNextTick.process._tickCallback (node.js:244:9)
[PARENT] Worker 9225 died. 3 dead of 3
[PARENT] All workers have died.
[PARENT] Fail
Command: out/Release/node /home/roman/wc/node/test/simple/test-dgram-multicast-multi-process.js

after:

=== release test-dgram-multicast-multi-process ===
Path: simple/test-dgram-multicast-multi-process
dgram.js:287
    throw new errnoException(errno, 'addMembership');
          ^
Error: addMembership ENODEV
    at new errnoException (dgram.js:356:11)
    at Socket.addMembership (dgram.js:287:11)
    at Object.<anonymous> (/home/roman/wc/node/test/simple/test-dgram-multicast-multi-process.js:224:16)
    at Module._compile (module.js:449:26)
    at Object.Module._extensions..js (module.js:467:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.runMain (module.js:487:10)
    at process.startup.processNextTick.process._tickCallback (node.js:244:9)
[PARENT] Worker 13141 died. 1 dead of 3

dgram.js:287
    throw new errnoException(errno, 'addMembership');
          ^
[PARENT] sent 'First message to send' to 224.0.0.114:12346
[PARENT] sent 'Second message to send' to 224.0.0.114:12346
[PARENT] sent 'Third message to send' to 224.0.0.114:12346
[PARENT] sent 'Fourth message to send' to 224.0.0.114:12346
[PARENT] sendSocket closed

dgram.js:287
    throw new errnoException(errno, 'addMembership');
          ^
Error: addMembership ENODEV
    at new errnoException (dgram.js:356:11)
    at Socket.addMembership (dgram.js:287:11)
    at Object.<anonymous> (/home/roman/wc/node/test/simple/test-dgram-multicast-multi-process.js:224:16)
    at Module._compile (module.js:449:26)
    at Object.Module._extensions..js (module.js:467:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.runMain (module.js:487:10)
    at process.startup.processNextTick.process._tickCallback (node.js:244:9)
[PARENT] Worker 13142 died. 2 dead of 3
Error: addMembership ENODEV
    at new errnoException (dgram.js:356:11)
    at Socket.addMembership (dgram.js:287:11)
    at Object.<anonymous> (/home/roman/wc/node/test/simple/test-dgram-multicast-multi-process.js:224:16)
    at Module._compile (module.js:449:26)
    at Object.Module._extensions..js (module.js:467:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.runMain (module.js:487:10)
    at process.startup.processNextTick.process._tickCallback (node.js:244:9)
[PARENT] Worker 13143 died. 3 dead of 3
[PARENT] All workers have died.
[PARENT] Fail
Command: out/Release/node /home/roman/wc/node/test/simple/test-dgram-multicast-multi-process.js