RFR: 8203290: [PPC64, s390] Check functionality of JDK-8199712 (Flight Recorder) [v5]

[Tyler Steele]

> Just in time for the holidays I have completed an implementation of the JFR functionality for AIX. As a side note, this is my first submission to OpenJDK 👋
> 
> ### Implementation notes and alternatives considered
> 
> After modifying the build system to allow the --enable-jvm-feature-jfr to work on AIX, my task was to implement the interfaces from os_perf.hpp. The os_perf_aix.cpp implementation that existed was, I believe, a copy of the Linux implementation. A review of the code in that file showed that NetworkInterface, CPUPerformanceInterface, and SystemProcessInterface would require modification to work on AIX. Using the Linux implementation as a guide, I initially expected to use files from the aix procfs like /proc/<pid>/psinfo, and /proc/<pid>/status in a manner similar to the Linux implementation. However, I ended up using libperfstat for all functionality required by the interfaces.
> 
> ### Testing
> 
> Testing for JFR seems to be quite light in the repo both before and after this change. In addition to performing manual testing, I have added some basic sanity checks that ensure events can be created and committed (using jtreg), and performs some basic checks on the results of the interface member functions (using gtest).
> 
> ### More notes
> 
> I've sent an email to the JFR group about a TOC overflow warning I encountered while building (for the release server target). I believe the fix is to pass -qpic=large when using the xlc toolchain, but my modifications to flags-cflags.m4 have not been successful in removing this warning.

Tyler Steele has updated the pull request incrementally with one additional commit since the last revision:

  Fix issue where network_interface pointer is not updated to newly created list

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6885/files
  - new: https://git.openjdk.java.net/jdk/pull/6885/files/4c0b1877..a286c9a4

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6885&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6885&range=03-04

  Stats: 3 lines in 1 file changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6885.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6885/head:pull/6885

PR: https://git.openjdk.java.net/jdk/pull/6885