RFR: 8258383: vmTestbase/gc/g1/unloading/tests/unloading_compilation_level[1, 2, 3] time out without TieredCompilation [v2]

[Tobias Hartmann]

> The test gets stuck while waiting for a compilation to succeed, because the corresponding compilation level is not available since Tiered Compilation is disabled (or `TieredStopAtLevel` is set). The tests should not be executed without Tiered Compilation (or if the requested compilation level is not available) and also check the output of `enqueueMethodForCompilation` for sanity.
> 
> Thanks,
> Tobias

Tobias Hartmann has updated the pull request incrementally with one additional commit since the last revision:

  Removed TieredCompilation flag from compilation level 4 tests

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2125/files
  - new: https://git.openjdk.java.net/jdk/pull/2125/files/0a31cbd7..c89cb5d6

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2125&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2125&range=00-01

  Stats: 6 lines in 6 files changed: 0 ins; 6 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2125.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2125/head:pull/2125

PR: https://git.openjdk.java.net/jdk/pull/2125