This only merges MDEV-12253, adapting it to MDEV-12602 which is already
present in 10.2 but not yet in the 10.1 revision that is being merged.

TODO: Error handling in crash recovery needs to be improved.
If a page cannot be decrypted (or read), we should cleanly abort
the startup. If innodb_force_recovery is specified, we should
ignore the problematic page and apply redo log to other pages.
Currently, the test encryption.innodb-redo-badkey randomly fails
like this (the last messages are from cmake -DWITH_ASAN):

2017-05-05 10:19:40 140037071685504 [Note] InnoDB: Starting crash recovery from checkpoint LSN=1635994
2017-05-05 10:19:40 140037071685504 [ERROR] InnoDB: Missing MLOG_FILE_NAME or MLOG_FILE_DELETE before MLOG_CHECKPOINT for tablespace 1
2017-05-05 10:19:40 140037071685504 [ERROR] InnoDB: Plugin initialization aborted at srv0start.cc[2201] with error Data structure corruption
2017-05-05 10:19:41 140037071685504 [Note] InnoDB: Starting shutdown...
i=================================================================
==5226==ERROR: AddressSanitizer: attempting free on address which was not malloc()-ed: 0x612000018588 in thread T0
    #0 0x736750 in operator delete(void*) (/mariadb/server/build/sql/mysqld+0x736750)
    #1 0x1e4833f in LatchCounter::~LatchCounter() /mariadb/server/storage/innobase/include/sync0types.h:599:4
    #2 0x1e480b8 in LatchMeta<LatchCounter>::~LatchMeta() /mariadb/server/storage/innobase/include/sync0types.h:786:17
    #3 0x1e35509 in sync_latch_meta_destroy() /mariadb/server/storage/innobase/sync/sync0debug.cc:1622:3
    #4 0x1e35314 in sync_check_close() /mariadb/server/storage/innobase/sync/sync0debug.cc:1839:2
    #5 0x1dfdc18 in innodb_shutdown() /mariadb/server/storage/innobase/srv/srv0start.cc:2888:2
    #6 0x197e5e6 in innobase_init(void*) /mariadb/server/storage/innobase/handler/ha_innodb.cc:4475:3