Merge with 5.2

sql/opt_range.h

@@ -274,6 +274,7 @@ public:
 
   virtual bool reverse_sorted() = 0;
   virtual bool unique_key_range() { return false; }
+  virtual bool clustered_pk_range() { return false; }
 
   /*
     Request that this quick select produces sorted output. Not all quick
@@ -593,6 +594,8 @@ public:
   THD *thd;
   virtual int read_keys_and_merge()= 0;
 
+  bool clustered_pk_range() { return test(pk_quick_select); }
+
   /* used to get rows collected in Unique */
   READ_RECORD read_record;
 };