Have the stack optimization in the code transform only reuse slots that are reachable and fix argument slot reuse on functions without return variables.

test/libyul/evmCodeTransform/stackReuse/function_argument_reuse_without_retparams.yul

@@ -0,0 +1,29 @@
+{
+  function f(x, y) {
+    mstore(0x80, x)
+    if calldataload(0) { sstore(y, y) }
+  }
+}
+// ====
+// stackOptimization: true
+// ----
+// PUSH1 0x17
+// JUMP
+// JUMPDEST
+// DUP1
+// PUSH1 0x80
+// MSTORE
+// POP
+// PUSH1 0x0
+// CALLDATALOAD
+// ISZERO
+// PUSH1 0x13
+// JUMPI
+// DUP1
+// DUP2
+// SSTORE
+// JUMPDEST
+// POP
+// JUMPDEST
+// JUMP
+// JUMPDEST