RFR: 8347270: Remove unix_getParentPidAndTimings and unix_getCmdlineAndUserInfo

[Matthias Baesken]

The functions unix_getParentPidAndTimings and unix_getCmdlineAndUserInfo in src/java.base/unix/native/libjava/ProcessHandleImpl_unix.c used to hold an implementation that was shared between Solaris and AIX. Linux and MacOS already had specific implementations. After the removal of the Solaris port, these two functions can be removed in favor of inline implementations of os_getParentPidAndTimings and os_getCmdlineAndUserInfo in src/java.base/aix/native/libjava/ProcessHandleImpl_aix.c.

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Commit messages:
 - JDK-8347270

Changes: https://git.openjdk.org/jdk/pull/23013/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23013&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347270
  Stats: 167 lines in 3 files changed: 57 ins; 108 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/23013.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23013/head:pull/23013

PR: https://git.openjdk.org/jdk/pull/23013