Remove assignments of the $MASTER_MYSOCK variable.

This variable is defined by default and one should not do it
directly as the socket variable is not available on Windows.

mysql-test/suite/funcs_1/t/is_table_constraints.test

@@ -132,7 +132,6 @@ eval $my_show1;
 eval $my_show2;
 
 --echo # Establish connection testuser1 (user=testuser1)
-let $MASTER_MYSOCK= query_get_value(SHOW VARIABLES LIKE 'socket', Value, 1);
 --replace_result $MASTER_MYPORT MYSQL_PORT $MASTER_MYSOCK MYSQL_SOCK
 connect (testuser1, localhost, testuser1, , db_datadict);
 SHOW GRANTS FOR 'testuser1'@'localhost';