splay tree and red-black tree for vm_map entry lookups.

I have ported the splay tree used in FreeBSD to look up vm_map entries. [1]
And written a reb-black tree that does the same (part of the vm_map_lookup_entry
taken from NetBSD) [2].

I havn't done any benchmarks on the two patches yet, but this should be done to
see which one is the best to use, and I hope you have some feedback for me.

1: http://leaf.dragonflybsd.org/~eirikn/splay-tree-freebsd-1.patch
2: http://leaf.dragonflybsd.org/~eirikn/vm_map-rb-tree-netbsd-eirikn.patch

-- 
Eirik Nygaard