Auto merge of rust-lang#88839 - nbdd0121:alignof, r=nagisa

Introduce NullOp::AlignOf

This PR introduces `Rvalue::NullaryOp(NullOp::AlignOf, ty)`, which will be lowered from `align_of`, similar to `size_of` lowering to `Rvalue::NullaryOp(NullOp::SizeOf, ty)`.

The changes are originally part of rust-lang#88700 but since it's not dependent on other changes and could have performance impact on its own, it's separated into its own PR.

clippy_utils/src/qualify_min_const_fn.rs

@@ -192,7 +192,7 @@ fn check_rvalue(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, def_id: DefId, rvalue: &Rv
                 ))
             }
         },
-        Rvalue::NullaryOp(NullOp::SizeOf, _) => Ok(()),
+        Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, _) => Ok(()),
         Rvalue::NullaryOp(NullOp::Box, _) => Err((span, "heap allocations are not allowed in const fn".into())),
         Rvalue::UnaryOp(_, operand) => {
             let ty = operand.ty(body, tcx);