Обсуждение: pgsql: Retry in FileRead and FileWrite if Windows returns

Log Message:
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Retry in FileRead and FileWrite if Windows returns ERROR_NO_SYSTEM_RESOURCES.
Also add a retry for Unixen returning EINTR, which hasn't been reported
as an issue but at least theoretically could be.  Patch by Qingqing Zhou,
some minor adjustments by me.

Modified Files:
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    pgsql/src/backend/storage/file:
        fd.c (r1.122 -> r1.123)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/file/fd.c.diff?r1=1.122&r2=1.123)