SHOW ENGINE INNODB MUTEX shows all mutexes and rw_locks. This can
be overwhelming particularly when the buffer pool is very large
(note that each block in buffer pool has at least one mutex, one
rw_lock and an additional mutex if rw_lock does not use atomics).
With this patch status of following mutexes and rw-locks is not shown:

1) block->mutex
2) block->lock
3) block->lock->mutex (if applicable)
4) All other mutexes and rw-locks for which number of os-waits are zero

Addresses issue# 179 rb://99

Approved by: Marko