RFR: 8344079: Minor fixes and cleanups to compiler lint-related code [v2]

[Maurizio Cimadamore]

On Mon, 2 Dec 2024 17:52:14 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> `log.warnIfEnabled(DEP_ANN, pos, Warnings.MissingDeprecatedAnnotation)`

Or, even better:

`log.warnIfEnabled(pos, Warnings.MissingDeprecatedAnnotation)`

(e.g. just use the warning key option for the `isEnabled` check)

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PR Review Comment: https://git.openjdk.org/jdk/pull/22056#discussion_r1866331563