Cranelift: Implement iadd_cout on x64 for 32- and 64-bit integers (#5285)

* Split the `iadd_cout` runtests by type

* Implement `iadd_cout` for 32- and 64-bit values on x64

* Delete trailing whitespace in `riscv/lower.isle`

cranelift/codegen/src/isa/x64/lower.rs

@@ -331,6 +331,7 @@ fn lower_insn_to_regs(
         | Opcode::F64const
         | Opcode::Null
         | Opcode::Iadd
+        | Opcode::IaddCout
         | Opcode::IaddIfcout
         | Opcode::SaddSat
         | Opcode::UaddSat
@@ -515,7 +516,6 @@ fn lower_insn_to_regs(
         | Opcode::IrsubImm
         | Opcode::IaddCin
         | Opcode::IaddIfcin
-        | Opcode::IaddCout
         | Opcode::IaddCarry
         | Opcode::IaddIfcarry
         | Opcode::IsubBin