[Metal][DXC] Metal shader conversion failing in DXC for `AddUint64`

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```hlsl
StructuredBuffer In : register(t0);
RWStructuredBuffer Out : register(u1);

[numthreads(1,1,1)]
void main() {
Out[0] = AddUint64(In[0], In[0]);
Out[1] = AddUint64(uint4(0xffffffff, 0xffffffff, 0, 0), uint4(1, 0, 0, 0));
uint4 Tmp = {AddUint64(In[1].xy, In[1].xy), AddUint64(In[1].zw, In[1].zw)};
Out[2] = Tmp;
uint4 Tmp2 = {AddUint64(In[2].xy, In[2].xy), AddUint64(In[2].zw, In[2].zw)};
Out[3] = Tmp2;
}
```
Error message:
```
Command Output (stderr):
--
/Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/llvm-project/build/bin/split-file /Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/OffloadTest/test/Feature/HLSLLib/adduint64.test /Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/llvm-project/build/tools/OffloadTest/test/mtl/Feature/HLSLLib/Output/adduint64.test.tmp # RUN: at line 68
+ /Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/llvm-project/build/bin/split-file /Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/OffloadTest/test/Feature/HLSLLib/adduint64.test /Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/llvm-project/build/tools/OffloadTest/test/mtl/Feature/HLSLLib/Output/adduint64.test.tmp
"/Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/DXC/build/bin/dxc-3.7" -metal -T cs_6_5 -Fo /Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/llvm-project/build/tools/OffloadTest/test/mtl/Feature/HLSLLib/Output/adduint64.test.tmp.o /Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/llvm-project/build/tools/OffloadTest/test/mtl/Feature/HLSLLib/Output/adduint64.test.tmp/source.hlsl # RUN: at line 69
+ /Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/DXC/build/bin/dxc-3.7 -metal -T cs_6_5 -Fo /Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/llvm-project/build/tools/OffloadTest/test/mtl/Feature/HLSLLib/Output/adduint64.test.tmp.o /Users/cbieneman/actions-runner/_work/offload-test-suite/offload-test-suite/llvm-project/build/tools/OffloadTest/test/mtl/Feature/HLSLLib/Output/adduint64.test.tmp/source.hlsl
Error occurred in Metal Shader Conversion
```

Start with OffloadTest/test/Feature/HLSLLib/adduint64.test and run the shown dxc-3.7 -metal command against the AddUint64 cases. Trace where Metal Shader Conversion fails and use the test to verify that all listed shader forms compile successfully.

Written by the indexing model from the issue text.