adding unit tests for Curl_llist_remove

  int unusedData_case1 = 1;

  int unusedData_case2 = 2;

  int unusedData_case3 = 3;

  struct curl_llist_element *head;

  struct curl_llist_element *element_next;

  struct curl_llist_element *element_prev;

  struct curl_llist_element *to_remove;

  size_t llist_size = Curl_llist_count( llist );

  int curlErrCode = 0;

  fail_unless( llist->size == 0 , "list initial size should be zero" );

           "success error code was returned\n" );

  }

  /* unit tests for Curl_llist_remove */

  /**

   * case 1:

   * list has >1 element, removing head

   * @assumptions:

   * 1: list size will be decremented by one

   * 2: head will be the head->next

   * 3: "new" head's previous will be NULL

   */

  head=llist->head;

  element_next = head->next;

  llist_size = Curl_llist_count( llist );

  Curl_llist_remove( llist , llist->head , NULL );

  fail_unless( Curl_llist_count(llist) ==  (llist_size-1) ,

		  "llist size not decremented as expected" );

  fail_unless( llist->head == element_next ,

		  "llist new head not modified properly" );

  fail_unless( llist->head->prev == NULL ,

		  "new head previous not set to null" );

  /**

   * case 2:

   * removing non head element, with list having >=2 elements

   * @setup:

   * 1: insert another element to the list to make element >=2

   * @assumptions:

   * 1: list size will be decremented by one ; tested

   * 2: element->previous->next will be element->next

   * 3: element->next->previous will be element->previous

   */

  Curl_llist_insert_next(llist, llist->head , &unusedData_case3 );

  llist_size = Curl_llist_count( llist );

  to_remove = llist->head->next;

  element_next = to_remove->next;

  element_prev = to_remove->prev;

  Curl_llist_remove( llist , to_remove , NULL );

  fail_unless( element_prev->next == element_next ,

		  "element previous->next is not being adjusted" );

  fail_unless( element_next->prev == element_prev ,

		  "element next->previous is not being adjusted" );

  /**

   * case 3:

   * removing the tail with list having >=1 element

   * @assumptions

   * 1: list size will be decremented by one ;tested

   * 2: element->previous->next will be element->next ;tested

   * 3: element->next->previous will be element->previous ;tested

   * 4: list->tail will be tail->previous

   */

  to_remove = llist->tail;

  element_prev = to_remove->prev;

  Curl_llist_remove( llist , to_remove , NULL );

  fail_unless( llist->tail == element_prev ,

		  "llist tail is not being adjusted when removing tail" );

  fail_unless( 1==0 , "making sure i'm compiling" );

  /**

   * case 4:

   * removing head with list having 1 element

   * @assumptions:

   * 1: list size will be decremented by one ;tested

   * 2: list head will be null

   * 3: list tail will be null

   */

  to_remove = llist->head;

  Curl_llist_remove( llist , to_remove , NULL );

  fail_unless( llist->head == NULL ,

		  "llist head is not NULL while the llist is empty" );

  fail_unless( llist->tail == NULL ,

  		  "llist tail is not NULL while the llist is empty" );

UNITTEST_STOP