Enable testing on Fedora Rawhide

[bkmgit]

Uses Fedora infrastructure https://packit.dev

Closes #3022

[bkmgit]

At present tests on ppc64 and build on aarch64 fail:
https://koji.fedoraproject.org/koji/taskinfo?taskID=144992149

[bkmgit]

For tests on Fedora to run, enable Packit integration. See:
https://packit.dev/docs/guide#github

[jan-wassenberg]

Nice. Probably good to wait a bit until we can remove CC0.

[jan-wassenberg]

Had a quick look at the failing builds.

aarch64 Error: unknown pseudo-op: `.lbe73430'
Probably OOM leading to truncated assembly file. I wonder if we can influence the flags, e.g. remove -ffat-lto-objects?
Might also help to split compare_test and/or disable some targets, I can do that.

ppc:

[----------] 1 test from HwyMemoryTestGroup/HwyMemoryTest
[ RUN      ] HwyMemoryTestGroup/HwyMemoryTest.TestAllLoadDup128/EMU128
i16x8 expect [0+ ->]:
  0x0001,0x0002,0x0003,0x0004,0x0005,0x0006,0x0007,
i16x8 actual [0+ ->]:
  0x0110,0x0000,0x0000,0x0000,0x0001,0x0002,0x0003,
Abort at memory_test.cc:393221: EMU128, i16x8 lane 0 mismatch: expected '0x0001', got '0x0110'.

This kind of thing is usually a compiler mistake caused by incorrect constant folding. I'm adding hwy::Unpredictable1() there which might help.

[bkmgit]

For aarch64 another issue is fixed by #3030
If fewer cores are used to compile, the build succeeds.

Failing build that resulted in #3030
https://koji.fedoraproject.org/koji/taskinfo?taskID=145011276
Build with fix:
https://koji.fedoraproject.org/koji/taskinfo?taskID=145019086

Disabling LTO also reduces memory requirements, but not using fat LTO objects might be sufficient in
most cases, see:
https://stackoverflow.com/questions/13799452/what-is-the-difference-in-gcc-between-lto-and-fat-lto-objects

[bkmgit]

AArch64 on Copr seems to have another failing test:
https://copr.fedorainfracloud.org/coprs/fed500/highway/build/10415978/

The following tests FAILED:
1546 - HwyReductionTestGroup/HwyReductionTest.TestAllMaskedReduceSum/SVE_256 (Subprocess aborted)
1558 - HwyReductionTestGroup/HwyReductionTest.TestAllMaskedReduceMax/SVE_256 (Subprocess aborted)

The machines used on Copr are likely different than the ones used on the koji tests. It may be helpful to log more information about the CPU microarchitecture being used and available RAM when doing tests.

Arm seems to have several other bugs:
#2974