As we know, vectors amortize the cost of adding new elements by reserving
space for multiple elements when full. This is useful but may lead to
allocating more memory than necessary.
`relibc` generally avoids over allocations by reserving the exact amount
of space when possible. I fixed a few areas that still over allocated or
reallocated unnecessarily by leveraging iterators that are more likely
to know sizes.
Josh Megnauth