Merge the latest trunk changes into the sessions branch.

FossilOrigin-Name: 832886b1e6edb916d9824924c7d88202f4eb1969

src/sqliteInt.h

@@ -1243,6 +1243,7 @@ struct VTable {
   sqlite3_vtab *pVtab;      /* Pointer to vtab instance */
   int nRef;                 /* Number of pointers to this structure */
   u8 bConstraint;           /* True if constraints are supported */
+  int iSavepoint;           /* Depth of the SAVEPOINT stack */
   VTable *pNext;            /* Next in linked list (see above) */
 };