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* Added new functions to OSI:
  - fixed_queue_init()
  - fixed_queue_length()
  - fixed_queue_try_remove_from_queue()
  - fixed_queue_try_peek_last()

* Renamed fixed_queue_try_peek() to fixed_queue_try_peek_first()

* Replaced usage of GKI queue functions with OSI fixed_queue functions:
  - GKI_init_q() -> fixed_queue_new(SIZE_MAX)
    NOTE: unlike GKI_init_q(), fixed_queue_new() allocates memory /
    state that needs to be released by calling fixed_queue_free()
  - GKI_enqueue() -> fixed_queue_enqueue()
  - GKI_dequeue() -> fixed_queue_try_dequeue()
    NOTE: fixed_queue_try_dequeue() is non-blocking
  - GKI_queue_length() -> fixed_queue_length()
  - GKI_queue_is_empty() -> fixed_queue_is_empty()
  - GKI_getfirst() -> fixed_queue_try_peek_first()
  - GKI_getlast() -> fixed_queue_try_peek_last()
  - GKI_remove_from_queue() -> fixed_queue_try_remove_from_queue()
  - Queue elements iteration.
    In the fixed_queue implementation we have to use the underlying
    list_t mechanism to iterate over the elements.
    OLD:
      p = GKI_getfirst(queue);
      ...
      while ((p = GKI_getnext(p) != NULL) {
         ...
      }
    NEW:
      list_t *list = fixed_queue_get_list(queue);
      for (const list_node_t *node = list_begin(list);
           node != list_end(list); node = list_next(node)) {
          p = list_node(node);
      }

* Remove initialization of the GKI module, because it is not needed
  anymore

* Removed unused files in GKI:
  gki/common/gki_common.h
  gki/ulinux/gki_int.h
  gki/ulinux/gki_ulinux.c

Change-Id: I3ff9464db75252d6faf7476a9ca67c88e535c51c