lib/list: remove LIST_HEAD macro

lib/list: remove LIST_HEAD macro

* the variable definition with hidden type is always horrible, for
  example:

	  int func() {
	    LIST_HEAD(foo);
	    ...
	  }

  the more readable is:

          int func() {
            struct list_head foo;

            INIT_LIST_HEAD(&foo);
            ...
          }

* the name LIST_HEAD conflict with /usr/include/sys/queue.h

* we use it only on two places in sulogin

Signed-off-by: Karel Zak <kzak@redhat.com>