Fix (hopefully) a race condition in a test. Wait until killed connection

is gone.

mysql-test/t/aborted_clients.test

@@ -3,12 +3,14 @@
 # status variable, but KILL connection does
 
 -- source include/not_embedded.inc
+-- source include/count_sessions.inc
 
 FLUSH STATUS;
 # Connect/Disconnect look that aborted_clients stays 0
 connect (con1,localhost,root,,);
 disconnect con1;
 connection default;
+-- source include/wait_until_count_sessions.inc
 # Check that there is 0 aborted clients so far
 SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME='aborted_clients';
 
@@ -19,8 +21,8 @@ connect(con2,localhost,root,,);
 KILL CONNECTION_ID();
 disconnect con2;
 connection default;
+-- source include/wait_until_count_sessions.inc
 
 # aborted clients must be 1 now
 SELECT VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_STATUS WHERE VARIABLE_NAME='aborted_clients';
 FLUSH STATUS;
-