[llvm] [InstCombine] Add missing fold for `fsqrt(select(b, c1, c2)) => select(b, fsqrt(c1), fsqrt(c2))` (PR #113084)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

The fold should only occur if at least one of the new sqrt calls will constant fold away.

https://github.com/llvm/llvm-project/pull/113084