Make spinlock stats work across open/close of the WT_CONNECTION.
Add spinlock statistics for __wt_spin_trylock() calls.

Add spinlock statistics for the number of lock attempts made from each
location.

Spinlock graphs are always per-second, but aren't listed in the
automatically generated file, add explicit tests in the scripts.
Merge branch 'develop' into spinlock-stats
We need to handle static "location ID" variables with both multiple
connections and connections being opened and closed.  Serialize the
"allocation" of location ID's and check in appropriate places if the
per-connection information they reference has been initialized for
any particular connection.
Unregister spinlocks from the connection when they are destroyed.
Merge pull request #805 from wiredtiger/spinlock-stats

Spinlock stats
Test doesn't need multiple scenarios.
The slot is read in a separate thread (the statistics logging thread),
call unregister first and add a barrier to ensure the slot is cleared
before the memory is free'd.   Technically, I think there's still a
race, but it's awfully small and this is code intended for performance
debugging, not production builds.