RFR: JDK-8308288: Fix xlc17 clang warnings in shared code

[Matthias Baesken]

On Thu, 25 May 2023 16:13:49 GMT, JoKern65 <duke at openjdk.org> wrote:

>> test/jdk/java/io/File/libGetXSpace.c line 128:
>> 
>>> 126: #else
>>> 127:     struct statfs buf;
>>> 128:     int result = statfs((char*)chars, &buf);
>> 
>> Is this working around a bug in IBM's declaration?
>> 
>> Also, pre-existing, the cast seems really suspicious.  The type of `chars` is `jchar*`, which is a
>> sequence of 16bit characters.  Does this actually work?  If so, how?
>
> This is IBMs declaration of statfs
> `extern int statfs(char *, struct statfs *);`
> So the compiler will not accept a `const char*`
> Indeed I do not know if this ever worked, but my change makes it not worse.

Here is the documentation of statfs on AIX  https://www.ibm.com/docs/en/aix/7.2?topic=s-statfs-fstatfs-statfs64-fstatfs64-ustat-subroutine  (showing the IBM declaration Joachim told us) .

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PR Review Comment: https://git.openjdk.org/jdk/pull/14146#discussion_r1206326207