[lworld] RFR: 8294462: [lworld] set system property valhalla.enableValhalla when -XX:+EnableValhalla [v3]

[Roger Riggs]

> Updated to set the system property after all of the option setting locations have been processed.
> Verified via -XshowSettings.

Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:

  Add jdk.internal.misc.ValhallaFeatures, similar to PreviewFeatures
  based on the -XX:+/-EnableValhalla command line flag.
  Removed the "valhalla.enableValhalla" System property.
  It is unused and not wanting test or app code to depend on it.

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Changes:
  - all: https://git.openjdk.org/valhalla/pull/769/files
  - new: https://git.openjdk.org/valhalla/pull/769/files/5b191f69..3da4a9e9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=769&range=02
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=769&range=01-02

  Stats: 173 lines in 7 files changed: 155 ins; 18 del; 0 mod
  Patch: https://git.openjdk.org/valhalla/pull/769.diff
  Fetch: git fetch https://git.openjdk.org/valhalla pull/769/head:pull/769

PR: https://git.openjdk.org/valhalla/pull/769