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 642839d254afcd1f90fff74d482dfaa3216d459c..0a4c1ea0d6e9ae04533054004b569393546cb272 100644
--- a/src/mark-compact.h
+++ b/src/mark-compact.h
@@ -660,6 +660,8 @@ class MarkCompactCollector {
 
   bool is_compacting() const { return compacting_; }
 
+  MarkingParity marking_parity() { return marking_parity_; }
+
  private:
   MarkCompactCollector();
   ~MarkCompactCollector();
@@ -692,6 +694,8 @@ class MarkCompactCollector {
 
   bool abort_incremental_marking_;
 
+  MarkingParity marking_parity_;
+
   // True if we are collecting slots to perform evacuation from evacuation
   // candidates.
   bool compacting_;