Avoid Division by Zero error.

This test case could throw either "ROWS parameter cannot be negative", or
"Division By Zero", depending on which gets evaluated first. Remove the
division by zero error, to make it more predictable.

src/test/regress/expected/qp_olap_windowerr.out

@@ -2546,7 +2546,7 @@ SELECT cf_olap_windowerr_sale.cn, TO_CHAR(COALESCE(REGR_R2(floor(cf_olap_windowe
 TO_CHAR(COALESCE(MAX(floor(cf_olap_windowerr_sale.qty)) OVER(order by cf_olap_windowerr_sale.ord, cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.pn desc rows between floor(cf_olap_windowerr_sale.qty-cf_olap_windowerr_sale.prc) preceding and current row ),0),'99999999.9999999'),
 TO_CHAR(COALESCE(MIN(floor(cf_olap_windowerr_sale.prc)) OVER(order by cf_olap_windowerr_sale.ord, cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.pn desc rows between floor(cf_olap_windowerr_sale.qty-cf_olap_windowerr_sale.prc) preceding and current row ),0),'99999999.9999999'),
 TO_CHAR(COALESCE(LEAD(cast(floor(cf_olap_windowerr_sale.prc/cf_olap_windowerr_sale.cn) as int),cast (floor(cf_olap_windowerr_sale.pn) as int),NULL) OVER(win2),0),'99999999.9999999'),
-TO_CHAR(COALESCE(LEAD(cast(floor(cf_olap_windowerr_sale.qty+cf_olap_windowerr_sale.cn) as int),cast (floor(cf_olap_windowerr_sale.prc/cf_olap_windowerr_sale.prc) as int),NULL) OVER(win3),0),'99999999.9999999')
+TO_CHAR(COALESCE(LEAD(cast(floor(cf_olap_windowerr_sale.qty+cf_olap_windowerr_sale.cn) as int),cast (floor(cf_olap_windowerr_sale.prc/(cf_olap_windowerr_sale.prc+1)) as int),NULL) OVER(win3),0),'99999999.9999999')
 FROM (SELECT cf_olap_windowerr_sale_ord.* FROM cf_olap_windowerr_sale_ord) cf_olap_windowerr_sale
 WINDOW win1 as (order by cf_olap_windowerr_sale.ord, cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.pn desc rows between floor(cf_olap_windowerr_sale.qty-cf_olap_windowerr_sale.prc) preceding and current row ),
 win2 as (order by cf_olap_windowerr_sale.ord, cf_olap_windowerr_sale.cn asc),

src/test/regress/sql/qp_olap_windowerr.sql

@@ -2828,7 +2828,7 @@ SELECT cf_olap_windowerr_sale.cn, TO_CHAR(COALESCE(REGR_R2(floor(cf_olap_windowe
 TO_CHAR(COALESCE(MAX(floor(cf_olap_windowerr_sale.qty)) OVER(order by cf_olap_windowerr_sale.ord, cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.pn desc rows between floor(cf_olap_windowerr_sale.qty-cf_olap_windowerr_sale.prc) preceding and current row ),0),'99999999.9999999'),
 TO_CHAR(COALESCE(MIN(floor(cf_olap_windowerr_sale.prc)) OVER(order by cf_olap_windowerr_sale.ord, cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.pn desc rows between floor(cf_olap_windowerr_sale.qty-cf_olap_windowerr_sale.prc) preceding and current row ),0),'99999999.9999999'),
 TO_CHAR(COALESCE(LEAD(cast(floor(cf_olap_windowerr_sale.prc/cf_olap_windowerr_sale.cn) as int),cast (floor(cf_olap_windowerr_sale.pn) as int),NULL) OVER(win2),0),'99999999.9999999'),
-TO_CHAR(COALESCE(LEAD(cast(floor(cf_olap_windowerr_sale.qty+cf_olap_windowerr_sale.cn) as int),cast (floor(cf_olap_windowerr_sale.prc/cf_olap_windowerr_sale.prc) as int),NULL) OVER(win3),0),'99999999.9999999')
+TO_CHAR(COALESCE(LEAD(cast(floor(cf_olap_windowerr_sale.qty+cf_olap_windowerr_sale.cn) as int),cast (floor(cf_olap_windowerr_sale.prc/(cf_olap_windowerr_sale.prc+1)) as int),NULL) OVER(win3),0),'99999999.9999999')
 FROM (SELECT cf_olap_windowerr_sale_ord.* FROM cf_olap_windowerr_sale_ord) cf_olap_windowerr_sale
 WINDOW win1 as (order by cf_olap_windowerr_sale.ord, cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.vn desc,cf_olap_windowerr_sale.pn desc rows between floor(cf_olap_windowerr_sale.qty-cf_olap_windowerr_sale.prc) preceding and current row ),
 win2 as (order by cf_olap_windowerr_sale.ord, cf_olap_windowerr_sale.cn asc),