Make tests more robust (clean up better after grant.test)

mysql-test/r/grant.result:
  Update test results to .test changes
mysql-test/t/grant.test:
  Drop users when done with them, to avoid skewing results of later tests.
  
  For example, running some test which examines the cardinality of the
  mysql.user table would fail if run right after this test, due to the
  extra users.

mysql-test/r/grant.result

@@ -1105,6 +1105,7 @@ ERROR 42000: SELECT command denied to user 'mysqltest_2'@'localhost' for table '
 DROP DATABASE mysqltest1;
 DROP DATABASE mysqltest2;
 DROP USER mysqltest_1@localhost;
+DROP USER mysqltest_2@localhost;
 use test;
 CREATE TABLE t1 (f1 int, f2 int);
 INSERT INTO t1 VALUES(1,1), (2,2);
@@ -1124,6 +1125,7 @@ f1	f2
 REVOKE UPDATE (f1) ON `test`.`t1` FROM 'mysqltest_1'@'localhost';
 REVOKE SELECT ON `test`.* FROM 'mysqltest_1'@'localhost';
 REVOKE ALL ON db27878.* FROM 'mysqltest_1'@'localhost';
+DROP USER mysqltest_1@localhost;
 DROP DATABASE db27878;
 use test;
 DROP TABLE t1;

mysql-test/t/grant.test

@@ -1122,6 +1122,7 @@ DROP DATABASE mysqltest1;
 DROP DATABASE mysqltest2;
 
 DROP USER mysqltest_1@localhost;
+DROP USER mysqltest_2@localhost;
 
 #
 # Bug#27878: Unchecked privileges on a view referring to a table from another 
@@ -1147,6 +1148,7 @@ connection default;
 REVOKE UPDATE (f1) ON `test`.`t1` FROM 'mysqltest_1'@'localhost';
 REVOKE SELECT ON `test`.* FROM 'mysqltest_1'@'localhost';
 REVOKE ALL ON db27878.* FROM 'mysqltest_1'@'localhost';
+DROP USER mysqltest_1@localhost;
 DROP DATABASE db27878;
 use test;
 DROP TABLE t1;