RFR: 8359596: Behavior change when both -Xlint:options and -Xlint:-options flags are given [v3]

[Archie Cobbs]

> My minor contribution to #24746 (which fixed [JDK-8354556](https://bugs.openjdk.org/browse/JDK-8354556)) accidentally introduced a change in the compiler's behavior when given conflicting lint flags like `-Xlint:options -Xlint:-options`. This PR restores the original behavior.
> 
> Although this might be considered a weird corner case, many build systems add flags in multiple stages and this can easily result in both flags being added, and so the behavior in this scenario needs to stay consistent. 
> 
> Basically the code was trying to be too clever; when the original logic is restored, the code gets simpler.

Archie Cobbs has updated the pull request incrementally with one additional commit since the last revision:

  Cleanups per review comments.

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/25840/files
  - new: https://git.openjdk.org/jdk/pull/25840/files/9e788319..f01f19dc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25840&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25840&range=01-02

  Stats: 27 lines in 4 files changed: 1 ins; 6 del; 20 mod
  Patch: https://git.openjdk.org/jdk/pull/25840.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25840/head:pull/25840

PR: https://git.openjdk.org/jdk/pull/25840