[crac] RFR: 8372863: [CRaC] Fix glibc IFUNC for AVX_Fast_Unaligned_Load [v2]

[Jan Kratochvil]

> glibc derives `AVX_Fast_Unaligned_Load` from CPU features but it is based on hardware CPU features and so disabling a CPU feature required for `AVX_Fast_Unaligned_Load` will not disable `AVX_Fast_Unaligned_Load` itself and it needs an explicit `GLIBC_TUNABLES` environment variable disabling.
> 
> There is a whole such category of 'preferred' bits. I hope no other bit causes crash (as they are there primarily for performance benefits) but that should be still verified.

Jan Kratochvil has updated the pull request incrementally with one additional commit since the last revision:

  jdk.vm.ci.common.JVMCIError: Missing CPU feature constants: [AVX_Fast_Unaligned_Load]

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

Changes:
  - all: https://git.openjdk.org/crac/pull/277/files
  - new: https://git.openjdk.org/crac/pull/277/files/30290977..ccba8d03

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=crac&pr=277&range=01
 - incr: https://webrevs.openjdk.org/?repo=crac&pr=277&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/crac/pull/277.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/277/head:pull/277

PR: https://git.openjdk.org/crac/pull/277