Add spaskalev/buddy_alloc

[spaskalev]

I wrote a custom buddy allocator with predictable storage and runtime costs.

It improves upon the textbook buddy allocator (e.g. the one TAOCP) in several ways

• Uses a optimal-fit strategy with a log complexity based on its tree depth. (not free lists)
• Supports non-power-of-two arena sizes
• Supports resizing arenas
• Supports rellocating the allocator and arena, for persistent heaps
• Metadata is external to the arena, making it safer from overwrites
• Full line and branch test coverage

It has been out for a while and seen some use in games - I think it might get some more publicity here, new users and further development. Thanks!

[spaskalev]

Hi team. Please consider merging this - I continue to support and actively develop buddy_alloc. Thanks!