New free list large object space.

More memory efficient, uses a std::set instead of multiset. Each
large object allocation has sizeof(size_t) * 2 bytes of overhead
without taking into account the std::set overhead. If debug is
enabled, then objects are mprotected as they are freed.

Added a large object test to space test.

Change-Id: I3e714e1afbed49208a4a7e60f9ef7d701a56801b