Fixes #179380: an assertion/crash in math.ipowi constant folding when the result type is i1. `IPowIOp::fold` constructed `APInt(width=1, val=1, isSigned=true)`. Signed i1 cannot represent +1 (range [-1, 0]), so APInt asserts (isIntN). This commit deactivates folding for `i1`. --------- Co-authored-by: Jakub Kuderski <kubakuderski@gmail.com>