Reusing Linux rbtree outside Linux

You may re-use this rbtree implementation in practice
For example, to implement malloc

A malloc implementation with rbtree is small
It is also reasonably fast and scales well


Surprisingly, a first-fit implementation is faster
                    if the number of blocks is not exceedingly large


And we are back the Pike's programming rules:
Rule 1. You can't know where a program is spending its time.
Rule 2. Always measure before you optimize.
Rule 3. Fancy algorithms are slow when n is small, and n is usually small.