RFR: 8261030: Avoid loading GenerateJLIClassesHelper at runtime

[Claes Redestad]

This moves the tracing methods added to GenerateJLIClassesHelper in JDK-8252725 to MethodHandleStatics, which avoids loading at runtime some code meant for jlink.

-------------

Commit messages:
 - Remove unused import, copyrights
 - Move tracing methods and constants from GenerateJLIClassesHelper to MethodHandleStatics

Changes: https://git.openjdk.java.net/jdk/pull/2376/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2376&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261030
  Stats: 69 lines in 4 files changed: 34 ins; 30 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2376.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2376/head:pull/2376

PR: https://git.openjdk.java.net/jdk/pull/2376