Memory leak in base64-t test

[Laurynas Biveinis]

==5966==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 345373 byte(s) in 500 object(s) allocated from:
    #0 0x7fc22472454a in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x9854a)
    #1 0x403006 in main /home/laurynas/mysql-server/unittest/mysys/base64-t.c:53
    #2 0x7fc223dbd82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)

Direct leak of 258468 byte(s) in 500 object(s) allocated from:
    #0 0x7fc22472454a in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x9854a)
    #1 0x4030c1 in main /home/laurynas/mysql-server/unittest/mysys/base64-t.c:62
    #2 0x7fc223dbd82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)

Direct leak of 254968 byte(s) in 500 object(s) allocated from:
    #0 0x7fc22472454a in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x9854a)
    #1 0x402fac in main /home/laurynas/mysql-server/unittest/mysys/base64-t.c:40
    #2 0x7fc223dbd82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)

SUMMARY: AddressSanitizer: 858809 byte(s) leaked in 1500 allocation(s).

[Laurynas Biveinis (laurynas-biveinis)]

https://github.com/percona/percona-server/pull/594, https://github.com/percona/percona-server/pull/595, https://github.com/percona/percona-server/pull/596

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-3459