Fix warnings introduced by define _GNU_SOURCE change

The change to define _GNU_SOURCE means that the compiler knows that
syscall returns a long, not an int -- so then it warns about the wrong
format characters for printing that value.

clamonacc/c-thread-pool/thpool.c

@@ -471,14 +471,14 @@ static struct job* jobqueue_pull(jobqueue* jobqueue_p){
 		  			break;
 
 		case 1:  /* if one job in queue */
-					logg(LOGG_DEBUG_NV, "jobqueue_pull: Thread %d pulled last job from queue.\n", syscall(SYS_gettid));
+					logg(LOGG_DEBUG_NV, "jobqueue_pull: Thread %ld pulled last job from queue.\n", syscall(SYS_gettid));
 					jobqueue_p->front = NULL;
 					jobqueue_p->rear  = NULL;
 					jobqueue_p->len = 0;
 					break;
 
 		default: /* if >1 jobs in queue */
-					logg(LOGG_DEBUG_NV, "jobqueue_pull: Thread %d pulled a job from queue.\n", syscall(SYS_gettid));
+					logg(LOGG_DEBUG_NV, "jobqueue_pull: Thread %ld pulled a job from queue.\n", syscall(SYS_gettid));
 					jobqueue_p->front = job_p->prev;
 					jobqueue_p->len--;
 					/* more than one job in queue -> post it */