RFR: JDK-8266797: Fix for 8266610 breaks the build on macos

[Vyom Tewari]

On Mon, 10 May 2021 10:44:10 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> OK, so what you are saying is that the path that references `S_ISBLK` is protected by `BLKGETSIZE64` that is guaranteed to be undefined on OS X? If so, this is (awkwardly) fine.
>
> I think Vymon took the code from FileDispatcherImpl_size0, which has been compiling on macOS without issues. I don't mind if we fix the issue with this PR or just back it out and fix it with another PR.

I am not the Mac expert, but i checked on my MacOS Laptop and i did not found "BLKGETSIZE64" defined in sys/stat.h.
As Alan already told that i  took the code from FileDispatcherImpl.size0 and followed the same pattern.

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PR: https://git.openjdk.java.net/jdk/pull/3943