[jdk17u] RFR: 8266239: Some duplicated javac command-line options have repeated effect

[Guoxiong Li]

Hi all,

I would like to backport this change about `javac` command option to jdk17u. The code applies cleanly.

The commit being backported was authored by Guoxiong Li on 14 Sep 2021 and was reviewed by Vicente Romero.

Best Regards,
-- Guoxiong

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Commit messages:
 - Backport d05494f98bad351532cdb769c9da6b6e2359b16e

Changes: https://git.openjdk.java.net/jdk17u/pull/110/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=110&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8266239
  Stats: 41 lines in 3 files changed: 39 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/110.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/110/head:pull/110

PR: https://git.openjdk.java.net/jdk17u/pull/110