RFR: 8134540: Much nearly duplicated code for PerfMemory support [v4]

[Harold Seigel]

> Please review this change to merge the Unix-like PerfMemory_*.cpp source files into a single PerfMemory_posix.cpp source file.
> 
> The changes were tested on Mach5 tiers 1-5 on Linux, Windows, and Mac OS, and cross-builds were done for the S390, arm32, ppc, and x86 platforms.
> 
> Thanks, Harold

Harold Seigel has updated the pull request incrementally with one additional commit since the last revision:

  8134540: fix AIX_ONLY typo

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2037/files
  - new: https://git.openjdk.java.net/jdk/pull/2037/files/282e6898..701b75ca

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2037&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2037&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2037.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2037/head:pull/2037

PR: https://git.openjdk.java.net/jdk/pull/2037