Compilation warnings on A32 build

[IgWod]

When building MAMBO on 32-bit Arm following warnings appear (also see GitHub Actions):

syscalls.c: In function ‘syscall_handler_pre’:
syscalls.c:233:32: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
  233 |       clone_args.child_stack = (void*)cl_args->stack + cl_args->stack_size;
      |                                ^
syscalls.c:234:25: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
  234 |       clone_args.ptid = (void*)cl_args->parent_tid;
      |                         ^a
syscalls.c:236:25: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
  236 |       clone_args.ctid = (void*)cl_args->child_tid;
      |                         

This is not an ideal situation and having it fixed would be desirable. Leaving it here for now as a good first issue.