Update wtperf Jenkins runner script to take explicit number of runs and
make most Jenkins jobs run once.
whitespace
Fixup LSM workers, so evicting old chunks doesn't stop checkpoints.

This change has two fixes:
* Ensure there are enough work units on the queue for checkpoints.
* Don't leave chunk reference counts out of wack.
Merge pull request #1406 from wiredtiger/lsm-flush-drop-fix

Fixup LSM workers, so evicting old chunks doesn't stop checkpoints.
Ignore returns from WT_ATOMIC_SUB4().
Fix a typo in a macro name.
Fix a comment.
Do a minimal check on each checkpoint's avail list, read it to ensure
it hasn't been corrupted.
Fix repeated deletes from the beginning of a tree to force eviction and avoid quadratic performance.

refs SERVER-16247
Merge branch 'develop' into wtstats-changes