[master] RFR: 8314863: [Lilliput] Revert changes in zRelocate, prevent ZGC with Lilliput [v3]

[Roman Kennke]

> The additions of SuspendibleThreadSet in [zRelocate.cpp](https://builds.shipilev.net/patch-openjdk-lilliput/src/hotspot/share/gc/z/zRelocate.cpp.udiff.html) can cause deadlocks. This problem can not easily be solved without major work in Lilliput. Let's revert those changes and prevent usage of ZGC together with Lilliput.
> 
> Testing:
>  - [ ] hotspot_gc +UCOH
>  - [ ] hotspot_gc -UCOH (default)

Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:

  Never exit hard, only change to -UCOH with warning

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

Changes:
  - all: https://git.openjdk.org/lilliput/pull/107/files
  - new: https://git.openjdk.org/lilliput/pull/107/files/eaed4926..4cfd48c6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=lilliput&pr=107&range=02
 - incr: https://webrevs.openjdk.org/?repo=lilliput&pr=107&range=01-02

  Stats: 6 lines in 1 file changed: 0 ins; 4 del; 2 mod
  Patch: https://git.openjdk.org/lilliput/pull/107.diff
  Fetch: git fetch https://git.openjdk.org/lilliput.git pull/107/head:pull/107

PR: https://git.openjdk.org/lilliput/pull/107