WiredTiger relies on certain operations being atomic. In particular, we perform loads and stores to integers up to sizeof(intptr_t) and rely on not getting torn reads.

We should investigate using the C11 standard atomic types for such shared data:

http://en.cppreference.com/w/c/atomic

Most usage is straightforward, but (among other things), simple increments cause a compiler warning, forcing the use of atomic_fetch_add, which would have avoided WT-2534.