Log Message:
Update zeromq to 2.2.0.

0MQ version 2.2.0 (Stable), released on 2012/04/04
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Changes
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* Fixed issue 349, add send/recv timeout socket options.

Bug fixes
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* Fixed issue 301, fix builds on HP-UX 11iv3 when using either gcc or aCC.

* Fixed issue 305, memory leakage when using dynamic subscriptions.

* Fixed issue 332, libzmq doesn't compile on Android NDK.

* Fixed issue 293, libzmq doesn't follow ZMTP/1.0 spec.

* Fixed issue 342, cannot build against zmq.hpp under C++11.