libtool was needed when NOX was directly linking against libopenflow.
Since it doesn't do that anymore, we can drop its use (and that makes
OpenFlow configure and build slightly faster).
Make LIST_FOR_EACH[_SAFE] variable take logically correct value upon loop termination.
Also, add regression tests for linked list routines, to ensure that this
change does not break code.
Also, add new macro LIST_FOR_EACH_REVERSE.