- Simplify the malloc-based allocator
- Correct the type signatures on malloc/calloc/realloc
- Make `heap_alloc/heap_free/heap_resize` API consistent across platforms
- Add the test bench for the allocator
- Move old allocator code to the test bench
- Fix `heap_resize` usage in `os2/env_linux.odin` to fit new API
requiring `old_size`