RFR: 8310405: Linker.Option.firstVariadicArg should specify which index values are valid [v2]

[Jorn Vernee]

> Improve the specification of `Linker.Option.firstVariadicArg`, by specifying more clearly which index values are valid.

Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:

  polish doc, review comments

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14565/files
  - new: https://git.openjdk.org/jdk/pull/14565/files/24bf486f..f6a111b9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14565&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14565&range=00-01

  Stats: 17 lines in 1 file changed: 5 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/14565.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14565/head:pull/14565

PR: https://git.openjdk.org/jdk/pull/14565