Add inlining for old optimizer.

test/cmdlineTests/optimizer_inliner_dynamic_reference_constructor/input.sol

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-3.0
+pragma solidity >=0.0;
+
+contract C {
+    constructor() { x = f; }
+    function() internal view returns (uint) x;
+
+    function a() public pure returns (uint) { return f(); } // this should be inlined
+    function h() public view returns (uint) { return x() + 1; }
+    function f() internal pure returns (uint) { return 6; }
+}