[llvm] VectorUtils: mark lrint, llrint as trivially vectorizable (PR #69945)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

Update: I attempted to break something by writing variants of programs with std::lrint and std::llrint that SLP would vectorize, and running it through clang. It seems that nothing is vectorized, and there are still libcalls to lrint and llrint. It seems that there is more work to be done, and #55208 won't be fixed with this patch. The good news is that this patch doesn't break anything, and should be okay to merge.

https://github.com/llvm/llvm-project/pull/69945