[clang] [llvm] [Triple] Make an target triple "os" for firmware (PR #176272)

[Saleem Abdulrasool via cfe-commits]

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@@ -757,6 +759,7 @@ static Triple::OSType parseOS(StringRef OSName) {
       .StartsWith("vulkan", Triple::Vulkan)
       .StartsWith("cheriotrtos", Triple::CheriotRTOS)
       .StartsWith("chipstar", Triple::ChipStar)
+      .StartsWith("firmware", Triple::Firmware)
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compnerd wrote:

This allows parsing without a vendor check. Is the vendor check elsewhere?

https://github.com/llvm/llvm-project/pull/176272