posix-cpu-timer: Unify the now redundant code in lookup_task

Now that both !thread paths through lookup_task call
thread_group_leader, unify them into the single test at the end of
lookup_task.

This unification just makes it clear what is happening in the gettime
special case of lookup_task.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

kernel/time/posix-cpu-timers.c

@@ -66,14 +66,13 @@ static struct task_struct *lookup_task(const pid_t pid, bool thread,
 	if (thread)
 		return same_thread_group(p, current) ? p : NULL;
 
-	if (gettime) {
 	/*
 	 * For clock_gettime(PROCESS) the task does not need to be
 	 * the actual group leader. task->signal gives
 	 * access to the group's clock.
 	 */
-		return (p == current || thread_group_leader(p)) ? p : NULL;
-	}
+	if (gettime && (p == current))
+		return p;
 
 	/*
 	 * For processes require that p is group leader.