8344159: Add lint warnings for unnecessary warning suppression

[archiecobbs]

This PR adds a new Lint category "suppression" and associated warnings for @SuppressWarnings annotations that are unnecessary because they don't actually suppress any warnings.

Summary of changes:

• Add a new lint category "suppression" (disabled by default) and an associated warning for @SuppressWarnings annotations that don't actually suppress any warnings.
• Update the LintMapper to keep track of which @SuppressWarnings suppressions have been validated¹ and (later) generate warnings about those that never were.
• Update Log.warning() so it automatically validates any current suppression of the warning's lint category in effect.
• Augment Lint.isEnabled() and Lint.isSuppressed() with a new parameter boolean validate that specifies whether to also validate any current suppression.
• Add new method Lint.isActive() to check whether a category is enabled or suppression of the category is being tracked - in other words, the calculation for the warning needs to be performed. This is used when the calculation of a warning is non-trivial making it worth checking whether it should be skipped.
• Update *.gmk build files to add -Xlint:-suppression flags so that the build doesn't break (the JDK itself contains hundreds of unnecessary @SuppressWarnings annotations).

Prerequisites to this PR:

• 8348611: Eliminate DeferredLintHandler and emit warnings after attribution #24584

¹ The suppression of a lint category is "validated" as soon as it suppresses some warning in that category

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change requires CSR request JDK-8356043 to be approved

Warning

 ⚠️ Found leading lowercase letter in issue title for 6723459: javac to flag where warning suppression is not required

Issues

• JDK-8344159: Add lint warnings for unnecessary warning suppression (Enhancement - P4)
• JDK-6723459: javac to flag where warning suppression is not required (Enhancement - P3)
• JDK-8356043: Add lint warnings for unnecessary warning suppression (CSR)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/25167/head:pull/25167
$ git checkout pull/25167

Update a local copy of the PR:
$ git checkout pull/25167
$ git pull https://git.openjdk.org/jdk.git pull/25167/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 25167

View PR using the GUI difftool:
$ git pr show -t 25167

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/25167.diff

[bridgekeeper]

@archiecobbs This pull request has been inactive for more than 8 weeks and will be automatically closed if another 8 weeks passes without any activity. To avoid this, simply issue a /touch or /keepalive command to the pull request. Feel free to ask for assistance if you need help with progressing this pull request towards integration!

[archiecobbs]

/touch

[openjdk]

@archiecobbs The pull request is being re-evaluated and the inactivity timeout has been reset.