message: Release instructions in CFG of deleted IRCode
  Summary: When an `IRCode` with editable `ControlFlowGraph` is destroyed, the instructions are inside the `Block`s' `IRList`s. To correctly destroy them, the CFG needs to assert ownership.
diff: @@ -575,6 +575,11 @@ IRList* deep_copy_ir_list(IRList* old_ir_list) {
  IRCode::IRCode() : m_ir_list(new IRList()) {}
  IRCode::~IRCode() {
  + // Let the CFG clean itself up.
  + if (m_cfg != nullptr && m_cfg->editable() && m_owns_insns) {
  + m_cfg->set_insn_ownership(true);
  + }
  +
  if (m_owns_insns) {
  m_ir_list->insn_clear_and_dispose();
  } else {
  