This is a manual merge from mysql-5.1-innodb of:

  revision-id: vasil.dimov@oracle.com-20100930102618-s9f9ytbytr3eqw9h
  committer: Vasil Dimov <vasil.dimov@oracle.com>
  timestamp: Thu 2010-09-30 13:26:18 +0300
  message:
    Fix a potential bug when using __sync_lock_test_and_set()

    TYPE __sync_lock_test_and_set (TYPE *ptr, TYPE value, ...)

    it is not documented what happens if the two arguments are of different
    type like it was before: the first one was lock_word_t (byte) and the
    second one was 1 or 0 (int).

    Approved by:	Marko (via IRC)