Optimize: Reduce memory cost for tracking active allocations.

Optimize: Reduce memory cost for tracking active allocations.

We split the hash into two, one for small allocations up to
numeric_limits<uint32_t>::max, and one for the bigger rest. This
allows us to reduce the cost by up to a factor of 2 for some apps.
A notable example here is heaptrack_gui itself, as it does tons of
small allocations for its lookup tables, which are long-lived.

In one test case this reduces the memory consumption of heaptrack by
up to 1GB for me.