[clang] [clang] Implement __builtin_rotate{left,right}g (PR #160259)

[Nikolas Klauser via cfe-commits]

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+// RUN: %clang_cc1 -fsyntax-only -verify %s
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philnik777 wrote:

Should the target be pinned? Then the `#ifdef`s wouldn't be necessary anymore I think.

https://github.com/llvm/llvm-project/pull/160259