RFR: 8310405: Linker.Option.firstVariadicArg should specify which index values are valid [v3]

[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 three additional commits since the last revision:

 - review comments
 - Update src/java.base/share/classes/java/lang/foreign/Linker.java
   
   Co-authored-by: Maurizio Cimadamore <54672762+mcimadamore at users.noreply.github.com>
 - Phrasing
   
   Co-authored-by: Maurizio Cimadamore <54672762+mcimadamore at users.noreply.github.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14565/files
  - new: https://git.openjdk.org/jdk/pull/14565/files/f6a111b9..41c678a7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14565&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14565&range=01-02

  Stats: 5 lines in 1 file changed: 0 ins; 0 del; 5 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