CPU may have interrupts disabled waiting for that spinlock too, and
will never acknowledge our tlb flush..

read the next pointer, and then unlock a node.  otherwise, the next pointer
changes and we try to unlock subsequent nodes that we never locked.

 - new crange api
 - fix several crange bugs (see comments)
 - better scoped_acquire
compiles but still buggy and missing tlb shootdowns

fix shadowing declarations

"non-inline namespace cannot be reopened as inline"

use std::atomic, though with operator->() for now, since that can only be overriden with a member function

use atomic<> for dir pointer in an inode