[libclc] libclc: Add amdgpu subgroup functions (PR #184845)

[Michał Górny via cfe-commits]

mgorny wrote:

I'm seeing test regression on Gentoo/arm64 after this change:

```
Start testing: Mar 07 08:52 UTC
----------------------------------------------------------
3/3 Testing: external-funcs-amdgcn-mesa-mesa3d
3/3 Test: external-funcs-amdgcn-mesa-mesa3d
Command: "/var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc/check_external_funcs.sh" "/var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc_build/amdgcn-mesa-mesa3d/libclc.bc" "/usr/lib/llvm/23/bin"
Directory: /var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc
"external-funcs-amdgcn-mesa-mesa3d" start time: Mar 07 08:52 UTC
Output:
----------------------------------------------------------
ERROR: 1 unresolved external functions detected in /var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc_build/amdgcn-mesa-mesa3d/libclc.bc
declare hidden i64 @_Z19get_local_linear_idv() local_unnamed_addr #3
<end of output>
Test time =   1.43 sec
----------------------------------------------------------
Test Failed.
"external-funcs-amdgcn-mesa-mesa3d" end time: Mar 07 08:52 UTC
"external-funcs-amdgcn-mesa-mesa3d" time elapsed: 00:00:01
----------------------------------------------------------

1/3 Testing: external-funcs-amdgcn--
1/3 Test: external-funcs-amdgcn--
Command: "/var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc/check_external_funcs.sh" "/var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc_build/amdgcn--/libclc.bc" "/usr/lib/llvm/23/bin"
Directory: /var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc
"external-funcs-amdgcn--" start time: Mar 07 08:52 UTC
Output:
----------------------------------------------------------
ERROR: 1 unresolved external functions detected in /var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc_build/amdgcn--/libclc.bc
declare dso_local i64 @_Z19get_local_linear_idv() local_unnamed_addr #3
<end of output>
Test time =   1.44 sec
----------------------------------------------------------
Test Failed.
"external-funcs-amdgcn--" end time: Mar 07 08:52 UTC
"external-funcs-amdgcn--" time elapsed: 00:00:01
----------------------------------------------------------

2/3 Testing: external-funcs-amdgcn-amd-amdhsa-llvm
2/3 Test: external-funcs-amdgcn-amd-amdhsa-llvm
Command: "/var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc/check_external_funcs.sh" "/var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc_build/amdgcn-amd-amdhsa-llvm/libclc.bc" "/usr/lib/llvm/23/bin"
Directory: /var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc
"external-funcs-amdgcn-amd-amdhsa-llvm" start time: Mar 07 08:52 UTC
Output:
----------------------------------------------------------
ERROR: 1 unresolved external functions detected in /var/tmp/portage/llvm-core/libclc-23.0.0.9999/work/libclc_build/amdgcn-amd-amdhsa-llvm/libclc.bc
declare hidden i64 @_Z19get_local_linear_idv() local_unnamed_addr #5
<end of output>
Test time =   1.64 sec
----------------------------------------------------------
Test Failed.
"external-funcs-amdgcn-amd-amdhsa-llvm" end time: Mar 07 08:52 UTC
"external-funcs-amdgcn-amd-amdhsa-llvm" time elapsed: 00:00:01
----------------------------------------------------------

End testing: Mar 07 08:52 UTC
```

https://github.com/llvm/llvm-project/pull/184845