include/queue.h: ensure prototypes match implementations

[orlitzky]

In the latest C23 standard, the prototype

int get_queue_id();

indicates that get_queue_id takes no arguments. This of course disagrees with its implementation, which takes one argument. C23 will be the default mode in GCC-15, where this leads to a build failure:

queue.c:57:5: error: conflicting types for 'get_queue_id'; have 'int(int)'
 57 | int get_queue_id(int id) {
    |     ^~~~~~~~~~~~
In file included from queue.c:30:
../include/queue.h:40:5: note: previous declaration of 'get_queue_id' with
type 'int(void)'
 40 | int get_queue_id();
    |     ^~~~~~~~~~~~

To fix it, we update the prototype for get_queue_id().