[llvm] [SPIRV] Filter disallows extensions for env (PR #150051)

[Michal Paszkowski via llvm-commits]

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@@ -104,6 +167,26 @@ static const std::map<std::string, SPIRV::Extension::Extension, std::less<>>
         {"SPV_KHR_float_controls2",
          SPIRV::Extension::Extension::SPV_KHR_float_controls2}};
 
+/*
+
+TODO: std::set_union is not constexpr in c++17. I would still like a way to make
+sure the environment lists are added.
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michalpaszkowski wrote:

Alternatively, `multiclass ExtensionOperand` could be extended in `SPIRVSymbolicOperands.td` to contain also environment requirements. This way we would not need maintain these lists here. Though, this does not need to be done in this PR.

https://github.com/llvm/llvm-project/pull/150051