RFR: 8299088: ClassLoader.c contains 2 JNI exception pending defect groups

[Justin Lu]

This PR removes the JNI Exception pending defect groups in ClassLoader.c. 

`getUTF()` throws an exception and subsequently returns `null`; the exception should either be cleared, or control returned to the JVM. `JNU_ThrowOutOfMemoryError(env, NULL);` should not be called again

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Commit messages:
 - Adress JNI Exception Pending errors

Changes: https://git.openjdk.org/jdk/pull/12934/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12934&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8299088
  Stats: 3 lines in 1 file changed: 0 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/12934.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12934/head:pull/12934

PR: https://git.openjdk.org/jdk/pull/12934