Do not allow cursor hints to use expressions containing subqueries. This

change fixes the problem seen in the previous check-in.

FossilOrigin-Name: bfefc57554853e467ee6aeaba8d08331406fa216

src/expr.c

@@ -1264,6 +1264,22 @@ int sqlite3ExprIsConstantOrFunction(Expr *p){
   return exprIsConst(p, 2);
 }
 
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+/*
+** Walk an expression tree.  Return 1 if the expression contains a
+** subquery of some kind.  Return 0 if there are no subqueries.
+*/
+int sqlite3ExprContainsSubquery(Expr *p){
+  Walker w;
+  memset(&w, 0, sizeof(w));
+  w.u.i = 1;
+  w.xExprCallback = sqlite3ExprWalkNoop;
+  w.xSelectCallback = selectNodeIsConstant;
+  sqlite3WalkExpr(&w, p);
+  return w.u.i==0;
+}
+#endif
+
 /*
 ** If the expression p codes a constant integer that is small enough
 ** to fit in a 32-bit integer, return 1 and put the value of the integer