[clang] [llvm] [X86] Honor MXCSR for AVX-512 CUR_DIRECTION FP intrinsics in strictfp funcs (PR #203521)

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Andarwinux wrote:

https://github.com/llvm/llvm-project/pull/200607#pullrequestreview-4396001386

> Target intrinsics are currently completely unsupported under strictfp. We need https://discourse.llvm.org/t/rfc-yet-another-strict-fp/90798 or similar before it will be possible to support them.
> 
> (Same for #200610 and #200608).

https://github.com/llvm/llvm-project/pull/203521