Add the new internal interface sqlite3DbNNFreeNN(db,ptr) where both the

db and ptr parameters are guaranteed to be non-NULL.  Use this where
appropriate to save more than 2 million CPU cycles on the standard
performance test.

FossilOrigin-Name: e5eaa80e81fdf86f2875a912b880272b8d099b82b08e945a7988c5dd0fe9d6b5

src/wherecode.c

@@ -2109,8 +2109,8 @@ Bitmask sqlite3WhereCodeOneLoopStart(
       }
       nConstraint++;
     }
-    sqlite3DbFree(db, zStartAff);
-    sqlite3DbFree(db, zEndAff);
+    if( zStartAff ) sqlite3DbNNFreeNN(db, zStartAff);
+    if( zEndAff ) sqlite3DbNNFreeNN(db, zEndAff);
 
     /* Top of the loop body */
     if( pLevel->p2==0 ) pLevel->p2 = sqlite3VdbeCurrentAddr(v);