[crac] RFR: 8353241: [CRaC] Support ZGC [v3]

[Radim Vansa]

> During my tests with https://github.com/CRaC/example-spring-boot I could not get the image size as low as with G1, but the presented changes improve the image footprint. As as anecdotal data, the image is 177 MB with G1 while 215 MB with ZGC (fastdebug build, `-Xmx1G`).

Radim Vansa has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains three commits:

 - Merge branch 'crac' into zgc
 - fixup
 - 8353241: CRaC ZGC support

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Changes: https://git.openjdk.org/crac/pull/219/files
  Webrev: https://webrevs.openjdk.org/?repo=crac&pr=219&range=02
  Stats: 104 lines in 10 files changed: 85 ins; 7 del; 12 mod
  Patch: https://git.openjdk.org/crac/pull/219.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/219/head:pull/219

PR: https://git.openjdk.org/crac/pull/219