Our "util.h" header is a grabbag of various different functions, where
many don't have a clear group they belong to. Our set of allocator
functions though can be clearly singled out as a single group of
functions that always belongs together. Furthermore, we will need to
implement additional functions relating to our allocators subsystem when
moving to pluggable allocators. Thus, we should just move these
functions into their own "alloc" module.