Fix an integer overflow problem in the sorter.

FossilOrigin-Name: 9d3351b8d713232133dad149c73fb2a27c72abb1
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 0763f08..b802d7a 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -981,6 +981,7 @@
   int nChange;                  /* Value returned by sqlite3_changes() */
   int nTotalChange;             /* Value returned by sqlite3_total_changes() */
   int aLimit[SQLITE_N_LIMIT];   /* Limits */
+  int nMaxSorterMmap;           /* Maximum size of regions mapped by sorter */
   struct sqlite3InitInfo {      /* Information used during initialization */
     int newTnum;                /* Rootpage of table being initialized */
     u8 iDb;                     /* Which db file is being initialized */