RFR: 8304434: [AIX] Update minimum xlclang version [v2]

[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 one additional commit since the last revision:

  Change min xlx FP level to 11

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/13086/files
  - new: https://git.openjdk.org/jdk/pull/13086/files/4bf83c43..030f2283

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13086&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13086&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 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