[issue2890] O_ASYNC and FASYNC should be defined if available

[Ismail Donmez]

Changes by Ismail Donmez <ismail at namtrac.org>:


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title: O_ASYNC and FASYNC should be defined for *nix systems -> O_ASYNC and FASYNC should be defined if available

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Tracker <report at bugs.python.org>
<http://bugs.python.org/issue2890>
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