Experimental change to the pcache interface to allow page buffers to be allocated separately from their associated container structures.

FossilOrigin-Name: c275c9d323cb1dccb031b199d413ac3a0b244fea
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 2171c15..46bec6a 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -2459,7 +2459,7 @@
   int nLookaside;                   /* Default lookaside buffer count */
   sqlite3_mem_methods m;            /* Low-level memory allocation interface */
   sqlite3_mutex_methods mutex;      /* Low-level mutex interface */
-  sqlite3_pcache_methods pcache;    /* Low-level page-cache interface */
+  sqlite3_pcache_methods2 pcache2;  /* Low-level page-cache interface */
   void *pHeap;                      /* Heap storage space */
   int nHeap;                        /* Size of pHeap[] */
   int mnReq, mxReq;                 /* Min and max heap requests sizes */