Don't translate errno. #443.
Merge pull request #445 from wiredtiger/wterrno

Don't translate errno for fopen calls. #443.
When opening a Bloom filter, reset immediately to avoid holding hazard references for long periods.
refs #440
Merge pull request #440 from wiredtiger/bloom-open-reset

Don't pin bloom leaf pages in cache on first access. It can cause hangs with multi-threaded workloads and a tiny cache.
It is not safe to set the DISCARD_CLOSE flag before a checkpoint.

This change alters the code to allow WT_BTREE_DISCARD_CLOSE to be passed
via a checkpoint. Also fixes a bug where we weren't unlocking a closed
btree handle properly.
Merge branch 'develop' into lsm-discard-btree