RFR 9: 8074818: Resolve disabled warnings for libjava

[Martin Buchholz]

On Tue, May 26, 2015 at 7:52 PM, Roger Riggs <Roger.Riggs at oracle.com> wrote:

>  Hi,
>
> Sadly, but not entirely unexpectedly there is an anomaly in the include
> files:
> It seems that Windows does not define O_SYNC and O_DSYNC.
> To make up for the absence
> jdk/src/java.base/share/native/libjava/io_util.h
> conditionally defines them.  There is no problem if the system include
> files appear
> first, but  in the other order, fcntl.h tries to re-define it.
> In the recommended order, there is no issue.
>

We should work hard to remove order dependencies in include files.

I see that io_util.h includes <fcntl.h>, but only on BSD.  Why not include
it wherever it is available, (which may be all supported platforms!) before
trying to define O_SYNC and D_SYNC?