Quit trying to clean up the boundary structures on exit, instead
initialize each boundary array element right before it's about to
be used. This is probably slightly more work, but it's less likely
to break in the field, the code to allocate a new boundary item
has to be correct otherwise we'd hit the end of the array and drop
core. Reference #1239.
Merge pull request #1241 from wiredtiger/initialize-boundary-at-use

Reconciliation boundary initialization cleanup.