RFR: 8339364: AIX build fails: various unused variable and function warnings

[Matthias Baesken]

We get a couple of warnings as errors on AIX because of unused variables or functions , for example :
/priv/jenkins/client-home/workspace/openjdk-jdk-dev-aix_ppc64-opt/jdk/src/java.base/unix/native/libjava/ProcessHandleImpl_unix.c:665:10: error: unused variable 'exePath' [-Werror,-Wunused-variable]
    char exePath[PATH_MAX];
         ^
/priv/jenkins/client-home/workspace/openjdk-jdk-dev-aix_ppc64-opt/jdk/src/java.base/unix/native/libjava/ProcessHandleImpl_unix.c:668:9: error: unused variable 'ret' [-Werror,-Wunused-variable]
    int ret;
        ^
/priv/jenkins/client-home/workspace/openjdk-jdk-dev-aix_ppc64-opt/jdk/src/java.base/unix/native/libjava/ProcessHandleImpl_unix.c:664:10: error: unused variable 'fn' [-Werror,-Wunused-variable]
    char fn[32];
         ^

This seems to be related to the recent make changes
8339156: Use more fine-granular clang unused warnings
https://bugs.openjdk.org/browse/JDK-8339156
(we use clang too on AIX)

-------------

Commit messages:
 - JDK-8339364

Changes: https://git.openjdk.org/jdk/pull/20812/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20812&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339364
  Stats: 61 lines in 14 files changed: 9 ins; 36 del; 16 mod
  Patch: https://git.openjdk.org/jdk/pull/20812.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20812/head:pull/20812

PR: https://git.openjdk.org/jdk/pull/20812