Fix sporadic failure of set_statement mtr test.

On Windows with low precision  (10-16 ms) timer used for timing queries,
the statement "set @@long_query_time=0.01" can log itself a slow if it
spawn more single timer tick.

The fix is to filter this query out  from "SELECT FROM mysql.slow_log"
results

mysql-test/r/set_statement.result

@@ -1056,7 +1056,7 @@ set statement slow_query_log=default for select @@slow_query_log;
 truncate table mysql.slow_log;
 set slow_query_log= 1;
 set global log_output='TABLE';
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 sql_text
 set @@long_query_time=0.01;
 #should be written
@@ -1064,7 +1064,7 @@ select sleep(0.1);
 sleep(0.1)
 0
 set @@long_query_time=@save_long_query_time;
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 sql_text
 select sleep(0.1)
 #---
@@ -1072,7 +1072,7 @@ select sleep(0.1)
 set statement long_query_time=0.01 for select sleep(0.1);
 sleep(0.1)
 0
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 sql_text
 select sleep(0.1)
 set statement long_query_time=0.01 for select sleep(0.1)
@@ -1083,7 +1083,7 @@ set statement slow_query_log=0 for select sleep(0.1);
 sleep(0.1)
 0
 set @@long_query_time=@save_long_query_time;
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 sql_text
 select sleep(0.1)
 set statement long_query_time=0.01 for select sleep(0.1)
@@ -1092,7 +1092,7 @@ set statement long_query_time=0.01 for select sleep(0.1)
 set statement long_query_time=0.01,log_slow_filter='full_scan' for select sleep(0.1);
 sleep(0.1)
 0
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 sql_text
 select sleep(0.1)
 set statement long_query_time=0.01 for select sleep(0.1)
@@ -1101,7 +1101,7 @@ set statement long_query_time=0.01 for select sleep(0.1)
 set statement long_query_time=0.01,log_slow_rate_limit=9999 for select sleep(0.1);
 sleep(0.1)
 0
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 sql_text
 select sleep(0.1)
 set statement long_query_time=0.01 for select sleep(0.1)
@@ -1110,7 +1110,7 @@ set statement long_query_time=0.01 for select sleep(0.1)
 set statement long_query_time=0.01,min_examined_row_limit=50 for select sleep(0.1);
 sleep(0.1)
 0
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 sql_text
 select sleep(0.1)
 set statement long_query_time=0.01 for select sleep(0.1)

mysql-test/t/set_statement.test

@@ -1003,34 +1003,34 @@ truncate table mysql.slow_log;
 set slow_query_log= 1;
 set global log_output='TABLE';
 
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 set @@long_query_time=0.01;
 --echo #should be written
 select sleep(0.1);
 set @@long_query_time=@save_long_query_time;
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 --echo #---
 --echo #should be written
 set statement long_query_time=0.01 for select sleep(0.1);
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 --echo #---
 set @@long_query_time=0.01;
 --echo #should NOT be written
 set statement slow_query_log=0 for select sleep(0.1);
 set @@long_query_time=@save_long_query_time;
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 --echo #---
 --echo #should NOT be written
 set statement long_query_time=0.01,log_slow_filter='full_scan' for select sleep(0.1);
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 --echo #---
 --echo #should NOT be written
 set statement long_query_time=0.01,log_slow_rate_limit=9999 for select sleep(0.1);
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 --echo #---
 --echo #should NOT be written
 set statement long_query_time=0.01,min_examined_row_limit=50 for select sleep(0.1);
-select sql_text from mysql.slow_log;
+select sql_text from mysql.slow_log where sql_text not like 'set @@long_query_time%';
 --echo #---
 #
 # log_slow_verbosity is impossible to check because results are not written