[lworld] RFR: 8325343: [lworld] java/lang/reflect/Proxy/ClassRestrictions.java fails with NPE

[Mandy Chung]

Trivial 1-line fix is to check if the type is found or not before calling `PrimitiveClass::asPrimaryType`.

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Commit messages:
 - 8325343: [lworld] java/lang/reflect/Proxy/ClassRestrictions.java fails with NPE

Changes: https://git.openjdk.org/valhalla/pull/996/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=996&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8325343
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/996.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/996/head:pull/996

PR: https://git.openjdk.org/valhalla/pull/996