flush tables before the crash in the crashing test

to close all system tables

mysql-test/suite/binlog/r/binlog_index.result

@@ -12,6 +12,7 @@ master-bin.000001	#
 master-bin.000002	#
 master-bin.000003	#
 master-bin.000004	#
+flush tables;
 purge binary logs TO 'master-bin.000004';
 Warnings:
 Warning	1612	Being purged log master-bin.000001 was not found

mysql-test/suite/binlog/t/binlog_index.test

@@ -26,6 +26,7 @@ flush logs;
 
 source include/show_binary_logs.inc;
 remove_file $MYSQLD_DATADIR/master-bin.000001;
+flush tables;
 
 # there must be a warning with file names
 replace_regex /\.[\\\/]master/master/;