RFR: 8329174: update CodeBuffer layout in comment after constants section moved

[Vladimir Kozlov]

On Thu, 28 Mar 2024 02:50:40 GMT, lusou-zhangquan <duke at openjdk.org> wrote:

> Enhancement [JDK-6961697](https://bugs.openjdk.org/browse/JDK-6961697) moved nmethod constants section before instruction section, but the layout scheme in codeBuffer.cpp was not changed correspondingly. The mismatch between layout scheme in source code and actual layout is misleading, so we'd better fix it.

Trivial.

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Marked as reviewed by kvn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18529#pullrequestreview-1966996552