[master] RFR: Don't warn when UCOH is on by default [v2]

[Stefan Karlsson]

> When running testing with UCOH enabled by default in the code and non-generational ZGC the JVM prints this warning, which causes multiple failures in the testing. I'd like to propose that we  (at least temporarily) only write this warning if the user explicitly asked for UCOH.

Stefan Karlsson has updated the pull request incrementally with one additional commit since the last revision:

  Re-enable Non-generational ZGC

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Changes:
  - all: https://git.openjdk.org/lilliput/pull/165/files
  - new: https://git.openjdk.org/lilliput/pull/165/files/823fa4ba..d6f58052

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=lilliput&pr=165&range=01
 - incr: https://webrevs.openjdk.org/?repo=lilliput&pr=165&range=00-01

  Stats: 6 lines in 1 file changed: 0 ins; 6 del; 0 mod
  Patch: https://git.openjdk.org/lilliput/pull/165.diff
  Fetch: git fetch https://git.openjdk.org/lilliput.git pull/165/head:pull/165

PR: https://git.openjdk.org/lilliput/pull/165