Integrated: Fix compilation with gcc 11.2

[Thomas Schatzl]

Hi all,

  please review this small change to add code that disables the `-Wnonnull` warning for `JvmtiThreadState::state_for_while_locked`; the warning/error seems to be in error.

Thanks,
  Thomas

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Commit messages:
 - Disable wrong warning

Changes: https://git.openjdk.java.net/loom/pull/109/files
 Webrev: https://webrevs.openjdk.java.net/?repo=loom&pr=109&range=00
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/loom/pull/109.diff
  Fetch: git fetch https://git.openjdk.java.net/loom pull/109/head:pull/109

PR: https://git.openjdk.java.net/loom/pull/109