[lworld] RFR: 8337585: [lworld] VM crashes if primitive type signatures are present in the LoadableDescriptors attribute

[Frederic Parain]

Prevent VM crash when LoadableDescriptor attribute contains signature of primitive types.

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Commit messages:
 - Support primitive descriptors in LoadableDescriptors attribute

Changes: https://git.openjdk.org/valhalla/pull/1190/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1190&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8337585
  Stats: 116 lines in 3 files changed: 115 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/1190.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1190/head:pull/1190

PR: https://git.openjdk.org/valhalla/pull/1190