This can serve to maria_chk to check that trids found in rows and keys
are not too big. Also used by Recovery when logs are lost.
Options --require-control-file, --datadir, --log-dir (yes, the dashes are
inconsistent but I imitated mysqld --datadir and --maria-log-dir) for
maria_chk.
Lock control file _before_ reading its content.


storage/maria/ha_maria.cc:
  new prototype
storage/maria/ma_check.c:
  A function to find the max trid in the system (consults transaction
  manager and control file), to check tables.
storage/maria/ma_checkpoint.c:
  new prototype
storage/maria/ma_control_file.c:
  Store max trid into control file, in a backward-compatible way
  (can still read old control files).
  Parameter to ma_control_file_open(), to not create the log if it's
  missing (maria_chk needs that).
  Lock control file _before_ reading its content.
  Fix for a segfault when reading an old control file (bzero() with a
  negative second argument)
storage/maria/ma_control_file.h:
  changes to the control file module's API
storage/maria/ma_init.c:
  When Maria shuts down cleanly, store max trid into control file.
storage/maria/ma_loghandler.c:
  new prototype
storage/maria/ma_recovery.c:
  During recovery, consult max trid stored in control file, in case it is
  bigger than what we found in log (case of logs manually removed by user).
storage/maria/ma_test1.c:
  new prototype
storage/maria/ma_test2.c:
  new prototype
storage/maria/maria_chk.c:
  New option --require-control-file (abort if control file not found),
  --datadir (path for control file (and for logs if --log-dir not specified)),
  --log-dir (path for logs).
  Try to open control file when maria_chk starts.
storage/maria/maria_read_log.c:
  new prototype
storage/maria/trnman.c:
  A new function to know max trid in transaction manager
storage/maria/trnman_public.h:
  New function
storage/maria/unittest/ma_control_file-t.c:
  new prototypes. Testing storing and retrieving the max trid to/from
  control file
storage/maria/unittest/ma_test_loghandler-t.c:
  new prototype
storage/maria/unittest/ma_test_loghandler_first_lsn-t.c:
  new prototype
storage/maria/unittest/ma_test_loghandler_max_lsn-t.c:
  new prototype
storage/maria/unittest/ma_test_loghandler_multigroup-t.c:
  new prototype
storage/maria/unittest/ma_test_loghandler_multithread-t.c:
  new prototype
storage/maria/unittest/ma_test_loghandler_noflush-t.c:
  new prototype
storage/maria/unittest/ma_test_loghandler_nologs-t.c:
  new prototype
storage/maria/unittest/ma_test_loghandler_pagecache-t.c:
  new prototype
storage/maria/unittest/ma_test_loghandler_purge-t.c:
  new prototype