[llvm] [libc++] Prevent calling the projection more than three times (PR #66315)

[Jocelyn Castellano via llvm-commits]

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@@ -37,9 +37,10 @@ struct __fn {
     _LIBCPP_ASSERT_UNCATEGORIZED(!bool(std::invoke(__comp, std::invoke(__proj, __high), std::invoke(__proj, __low))),
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pandaninjas wrote:

I think we don't need a similar fix in `std::clamp` because `std::clamp` doesn't support using a projection

https://github.com/llvm/llvm-project/pull/66315