[lworld] RFR: 8337547: Add LoadableDescriptors to comments for class loading

[Coleen Phillimore]

This change adds comments for LoadableDescriptors for inline field layout processing to the class loading comments.  The other changes are to make the valhalla version of placeholders and systemDictionary match what is in mainline.  In mainline, interface and super class calls resolve_super_or_fail, otherwise we call resolve_with_circularity_detection.  There are some other comments in mainline in these files that aren't great, that are not addressed here in the Valhalla version.
Tested with tier1 locally.

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Commit messages:
 - adjust blank line
 - 8337547: Add LoadableDescriptors to comments for class loading

Changes: https://git.openjdk.org/valhalla/pull/1594/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1594&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8337547
  Stats: 26 lines in 5 files changed: 3 ins; 3 del; 20 mod
  Patch: https://git.openjdk.org/valhalla/pull/1594.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1594/head:pull/1594

PR: https://git.openjdk.org/valhalla/pull/1594