RFR: 8304434: [AIX] Update minimum xlclang version [v3]

[Tyler Steele]

> Minor changes to the build system to recognize and warn that an incompatible toolchain is detected.

Tyler Steele has updated the pull request incrementally with two additional commits since the last revision:

 - Trivial II
 - Trivial I

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13086/files
  - new: https://git.openjdk.org/jdk/pull/13086/files/030f2283..d5ed186a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13086&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13086&range=01-02

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13086.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13086/head:pull/13086

PR: https://git.openjdk.org/jdk/pull/13086