[clang] [HLSL] update default validator version to 1.8. (PR #104040)

[Cooper Partin via cfe-commits]

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@@ -283,14 +283,6 @@ HLSLToolChain::TranslateArgs(const DerivedArgList &Args, StringRef BoundArch,
     DAL->append(A);
   }
 
-  // Add default validator version if not set.
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coopp wrote:

This was removed.  Do we still need to fallback to a default here or does the change in Options.td take care of all of that?

https://github.com/llvm/llvm-project/pull/104040