thread_id is casted to guint64, which is throwing build error. Changing it to guint

The errors are 


gstrusage.c: In function 'do_stats':
gstrusage.c:241:37: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
   gst_tracer_record_log (tr_thread, (guint64)thread_id, ts,


gst-stats.c: In function ‘new_pad_stats’:
gst-stats.c:162:22: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
   stats->thread_id = (gpointer) thread_id;
                      ^
gst-stats.c: In function ‘do_thread_rusage_stats’:
gst-stats.c:395:36: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
   thread_stats = get_thread_stats ((gpointer) thread_id);