Age code to allow reclaiming old unexecuted functions

src/mark-compact.h

Index: src/mark-compact.h
diff --git a/src/mark-compact.h b/src/mark-compact.h
index 7ab83c41e56a0f392ca68bf5b8ea1ec4507ec652..cce8d00ea8bd63edd7d355dc1ef84d4b1ceedc53 100644
--- a/src/mark-compact.h
+++ b/src/mark-compact.h
@@ -646,6 +646,8 @@ class MarkCompactCollector {
 
   bool is_compacting() const { return compacting_; }
 
+  MarkingParity marking_parity() { return marking_parity_; }
+
  private:
   MarkCompactCollector();
   ~MarkCompactCollector();
@@ -678,6 +680,8 @@ class MarkCompactCollector {
 
   bool abort_incremental_marking_;
 
+  MarkingParity marking_parity_;
+
   // True if we are collecting slots to perform evacuation from evacuation
   // candidates.
   bool compacting_;