[clang] Cir neon rounding (PR #195021)

[Jiahao Guo via cfe-commits]

https://github.com/E00N777 commented:

Thank you for your contribution. 
Could you please write the commit message and summary in more detail? You can refer to:  https://github.com/llvm/llvm-project/pull/194229

https://github.com/llvm/llvm-project/pull/195021