make func_misc portable

on different systems sprintf("%.3", 1.555499999999999) behaves differently

mysql-test/r/func_misc.result

-select format(1.5555,0),format(123.5555,1),format(1234.5555,2),format(12345.5555,3),format(123456.5555,4),format(1234567.5555,5),format("12345.2399",2);
-format(1.5555,0)	format(123.5555,1)	format(1234.5555,2)	format(12345.5555,3)	format(123456.5555,4)	format(1234567.5555,5)	format("12345.2399",2)
-2	123.6	1,234.56	12,345.555	123,456.5555	1,234,567.55550	12,345.24
+select format(1.5555,0),format(123.5555,1),format(1234.5555,2),format(12345.55555,3),format(123456.5555,4),format(1234567.5555,5),format("12345.2399",2);
+format(1.5555,0)	format(123.5555,1)	format(1234.5555,2)	format(12345.55555,3)	format(123456.5555,4)	format(1234567.5555,5)	format("12345.2399",2)
+2	123.6	1,234.56	12,345.556	123,456.5555	1,234,567.55550	12,345.24
 select inet_ntoa(inet_aton("255.255.255.255.255.255.255.255"));
 inet_ntoa(inet_aton("255.255.255.255.255.255.255.255"))
 NULL

mysql-test/t/func_misc.test

@@ -2,7 +2,7 @@
 # Testing of misc functions
 #
 
-select format(1.5555,0),format(123.5555,1),format(1234.5555,2),format(12345.5555,3),format(123456.5555,4),format(1234567.5555,5),format("12345.2399",2);
+select format(1.5555,0),format(123.5555,1),format(1234.5555,2),format(12345.55555,3),format(123456.5555,4),format(1234567.5555,5),format("12345.2399",2);
 
 select inet_ntoa(inet_aton("255.255.255.255.255.255.255.255"));
 select inet_aton("255.255.255.255.255"),inet_aton("255.255.1.255"),inet_aton("0.1.255");