Fix deadlock issue with burst_buffer/cray when a newly created burst

buffer is found.

Bug 2576

What happened was a function was doing a double read lock which isn't
awesome to begin with, but not really horrible (if all you are doing is
read locks anyway).  The problem was after the first lock was locked a
different thread was going for a write lock and so when the second
read lock came in it created deadlocked.