Add additional DBSTATUS options for measuring the hit and miss rates against
the lookaside memory pool - information useful in tuning the lookaside size.
Currently experimental pending analysis of performance impact.

FossilOrigin-Name: 34613f1dc54c638531ca2f5907b71fbe8841233e
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 4f0e08e..5233e99 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -737,6 +737,7 @@
   u8 bMalloced;           /* True if pStart obtained from sqlite3_malloc() */
   int nOut;               /* Number of buffers currently checked out */
   int mxOut;              /* Highwater mark for nOut */
+  int anStat[3];          /* 0: hits.  1: size misses.  2: full misses */
   LookasideSlot *pFree;   /* List of available buffers */
   void *pStart;           /* First byte of available memory space */
   void *pEnd;             /* First byte past end of available space */