RFR: 8370520: GenShen: Track and report on promotion failures

[Francesco Andreuzzi]

On Thu, 23 Oct 2025 22:46:00 GMT, William Kemper <wkemper at openjdk.org> wrote:

> Keep track of promotion failures. Report the number of failures and total number of bytes that could not be promoted. These changes were hoisted out of https://github.com/openjdk/jdk/pull/27632.

Marked as reviewed by fandreuzzi (Author).

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PR Review: https://git.openjdk.org/jdk/pull/27962#pullrequestreview-3375098543