RFR: 8341791: Fix ExceptionOccurred in java.prefs

[Justin Lu]

Please review this PR which fixes incorrect usage of `jthrowable ExceptionOccurred(JNIEnv *env)` within _java.prefs_.

This corrects instances where the return value is being treated as a boolean. Such occurrences are replaced with `jboolean ExceptionCheck(JNIEnv *env)`.

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Commit messages:
 - init

Changes: https://git.openjdk.org/jdk/pull/21427/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21427&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341791
  Stats: 9 lines in 1 file changed: 0 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/21427.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21427/head:pull/21427

PR: https://git.openjdk.org/jdk/pull/21427