RFR: 8225354: serviceability/jvmti/ModuleAwareAgents/ThreadStart failed with Didn't get ThreadStart events in VM early start phase!

[Serguei Spitsyn]

The test incorrectly expects that some system threads must be started in the `early JVMTI_PHASE_START` phase. However, there is a race here and it is possible that the `JVMTI_PHASE_LIVE` phase is reached before any system thread has been started. The fix is to wait for the first `THREAD_START` event at the `VM_INIT` event.

The update includes some other changes and minor refactoring:
 - the file `libMAAThreadStart.c` has been renamed to `libMAAThreadStart.cpp`
 - the test library `jvmti_common.hpp` is used where it is possible
 - static variable `printdump` has been removed
 - the static block with `loadLibrary` has been removed from the `MAAThreadStart.java`
 
 Testing:
  - ran the modified test locally
  - TBD: submit mach5 tiers 1-5

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Commit messages:
 - 8225354: serviceability/jvmti/ModuleAwareAgents/ThreadStart failed with Didn't get ThreadStart events in VM early start phase!

Changes: https://git.openjdk.org/jdk/pull/25948/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25948&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8225354
  Stats: 331 lines in 4 files changed: 141 ins; 189 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/25948.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25948/head:pull/25948

PR: https://git.openjdk.org/jdk/pull/25948