Rollup merge of #49965 - nikic:fix-49622, r=rkruppe

Remove warning about f64->f32 cast being potential UB

As discussed in #15536, the LLVM documentation incorrect described overflowing f64->f32 casts as being undefined behavior. LLVM never treated them as such, and the documentation has been adjusted in https://reviews.llvm.org/rL329065. As such, this warning can now be removed.

Closes #49622.

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I could not find any existing test checking for this warning. Should I be adding a test for the absence of the warning instead?