Bug#22278455: MYSQL 5.5:RPL_BINLOG_INDEX FAILS IN VALGRIND.

Problem:
=======
rpl_binlog_index.test fails with following valgrind error.

line
Conditional jump or move depends on uninitialised value(s)
at 0x4C2F842: __memcmp_sse4_1 (in /usr/lib64/valgrind/
vgpreload_memcheck-amd64-linux.so)
0x739E39: find_uniq_filename(char*) (log.cc:2212)
0x73A11B: MYSQL_LOG::generate_new_name(char*, char const*)
(log.cc:2492)
0x73A1ED: MYSQL_LOG::init_and_set_log_file_name(char const*,
char const*, enum_log_type, cache_type) (log.cc:2289)
0x73B6F5: MYSQL_BIN_LOG::open(char const*, enum_log_type,


Analysis and fix:
=================
This issue was fixed as part of Bug#20459363 fix in 5.6 and
above. Hence backporting the fix to MySQL-5.5.

sql/log.cc

-/* Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -2209,7 +2209,7 @@ static int find_uniq_filename(char *name)
   file_info= dir_info->dir_entry;
   for (i= dir_info->number_off_files ; i-- ; file_info++)
   {
-    if (memcmp(file_info->name, start, length) == 0 &&
+    if (strncmp(file_info->name, start, length) == 0 &&
 	test_if_number(file_info->name+length, &number,0))
     {
       set_if_bigger(max_found,(ulong) number);