This LIFO test set covers the following scenarios.

nano_fiber_lifo_get(TICKS_UNLIMITED)
  - Getting an item from an emtpy LIFO (involves blocking and waking)
  - Getting an item from a non-empty LIFO (no blocking)

nano_task_lifo_get(TICKS_UNLIMITED)
  - Getting an item from an emtpy LIFO (involves blocking and waking)
  - Getting an item from a non-empty LIFO (no blocking)

nano_isr_lifo_get(TICKS_NONE)
  - Getting an item from a non-empty LIFO (no blocking)
  - Getting an item from an empty LIFO (no blocking, returns NULL)

nano_fiber_lifo_get(TICKS_NONE)
  - Getting an item from a non-empty LIFO (no blocking)
  - Getting an item from an empty LIFO (no blocking, returns NULL)

nano_task_lifo_get(TICKS_NONE)
  - Getting an item from a non-empty LIFO (no blocking)
  - Getting an item from an empty LIFO (no blocking, returns NULL)

nano_fiber_lifo_put
  - Waking a task blocked on an empty LIFO
  - Putting an item into an empty LIFO that upon which nothing is blocked
  - Putting an item into a non-empty LIFO

nano_task_lifo_put
  - Waking a fiber blocked on an empty LIFO
  - Putting an item into an empty LIFO that upon which nothing is blocked
  - Putting an item into a non-empty LIFO

nano_isr_lifo_put
  - Putting an item into an empty LIFO that upon which nothing is blocked
  - Putting an item into a non-empty LIFO