RFR: 8304434: [AIX] Update minimum xlclang version

[Martin Doerr]

On Fri, 17 Mar 2023 22:36:24 GMT, Tyler Steele <tsteele at openjdk.org> wrote:

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

LGTM. I think the reason for this PR is another issue? If so, please link the JBS issues as "relates to".
@MBaesken: Please take a look.

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PR Comment: https://git.openjdk.org/jdk/pull/13086#issuecomment-1476860602