[clang] [Headers] [ARM64EC] Fix extra tokens inside intrin0.h preprocessor directive (PR #112066)

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llvmbot wrote:

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>I think it's backport worthy. It's very small and has a near zero regression risk, and is a quite obvious fix. It might be a bit late for 19.1.2 which should be cut tomorrow, but should probably make it for 19.1.3.
>
>Just add this PR to the right 19.x milestone and type a `/cherry-pick` comment here with the commit hash, and the bots should do the rest.

Error: Command failed due to missing milestone.

https://github.com/llvm/llvm-project/pull/112066