can crash under load

Resizing a key cache while it was in heavy use could crash the
server. There were several race conditions.

I reworked some of the algorithms to fix the race conditions.

No test case. Repeating the crashes requires heavy concurrent
load on the key cache. A test script is attached to the bug report.

More explanations to the changes are contained in a text file
attached to the bug report.

into  mysql.com:/home/svoj/devel/mysql/merge/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/merge/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/merge/mysql-5.0-engines

into  mysql.com:/home/svoj/devel/mysql/merge/mysql-5.0-engines

into  chilla.local:/home/mydev/mysql-5.0-bug24607

into  chilla.local:/home/mydev/mysql-5.1-bug24607

into  chilla.local:/home/mydev/mysql-5.1-bug24607

After merge fix

into  chilla.local:/home/mydev/mysql-5.0-bug24607

Fixed test. On 32-bit machines which compile without
-DBIG_TABLES, MAX_ROWS is truncated to a 32-bit value.
Using a value below 4G is portable.

into  kahlann.erinye.com:/home/df/mysql/build/mysql-5.0-build-work

into  kahlann.erinye.com:/home/df/mysql/build/mysql-5.1-build-work

into  mysql.com:/home/svoj/devel/mysql/BUG24401/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG24401/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG24401/mysql-5.0-engines

into  mysql.com:/home/svoj/devel/mysql/BUG24401/mysql-5.0-engines

into  mysql.com:/home/svoj/devel/mysql/BUG24401/mysql-4.1-engines

into  willster.(none):/home/stewart/Documents/MySQL/5.0/ndb-work

into  willster.(none):/home/stewart/Documents/MySQL/5.1/ndb-work

into  poseidon.mysql.com:/home/tomas/mysql-5.0-ndb

into  chilla.local:/home/mydev/mysql-4.1-bug24607

into  production.mysql.com:/usersnfs/mjorgensen/bktrees/mysql-5.1-build

into  chilla.local:/home/mydev/mysql-5.0-bug24607

into  xiphis.org:/home/antony/work2/p1-bug25396.5

into  chilla.local:/home/mydev/mysql-5.1-bug24607

into  clam.ndb.mysql.com:/export/space/pekka/ndb/version/my50-ndb

into  clam.ndb.mysql.com:/export/space/pekka/ndb/version/my51-ndb

into  mysql.com:/data0/mysqldev/users/tomas/mysql-5.1-build

into  willster.(none):/home/stewart/Documents/MySQL/5.0/bug25487

into  willster.(none):/home/stewart/Documents/MySQL/5.1/bug25567

into  willster.(none):/home/stewart/Documents/MySQL/5.1/bug25567

  "Valgrind leak in closecon_handlerton"
  plugin_shutdown() calls plugin_deinitialize() which calls ha_finalize_handlerton().
  ndbcluster_end() fails to wait for the ndb utility thread to exit which results in
  the handlerton struct being freed before the ndb utility thread has destroyed it's THD
  but before the plugin has been marked as UNINITIALIZED

Bug is caused by misuse of abort_loops variable and not locking mutex during calls to
pthread condition variable functions causing a race in valgrind's pthread_cond_wait
implementation.

into  mysql.com:/home/svoj/devel/mysql/BUG24401/mysql-5.1-engines

into  mysql.com:/home/svoj/devel/mysql/BUG24401/mysql-5.0-engines

into  clam.ndb.mysql.com:/export/space/pekka/ndb/version/my51-ndb