[clang] [llvm] [x86] Add tan intrinsic part 4 (PR #90503)

[Farzon Lotfi via cfe-commits]

farzonl wrote:

> Nit: the `declare` is not necessary anymore. You touched the IRTranslator without a test at, e.g., https://github.com/llvm/llvm-project/blob/main/llvm/test/CodeGen/AArch64/GlobalISel/arm64-irtranslator.ll

The aarch64 backend tag is a misnomer because adding `G_FTAN` caused the legalizer to complain in this arm64 test case: llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir

I could add
```
declare float @llvm.tan.f32(float)
define float @test_tan_f32(float %x) {
  ; CHECK-LABEL: name:            test_tan_f32
  ; CHECK: %{{[0-9]+}}:_(s32) = G_FTAN %{{[0-9]+}}
  %y = call float @llvm.tan.f32(float %x)
  ret float %y
}
```
But I feel like this should be added when a tan intrinsic lowering is done for arm64 in llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

https://github.com/llvm/llvm-project/pull/90503