bfs: Temporarily conflict on SCHEDSTATS when SCHED_BFS is enabled

In kernel v4.5.2, the stable-queue merged the following commit:

cb25176
sched/debug: Make schedstats a runtime tunable that is disabled by
default

This is a nice optimization but requires time to properly port.  For
now, conflict on BFS so when SCHED_BFS is enabled, SCHEDSTATS disables
automatically.

lib/Kconfig.debug

@@ -876,7 +876,7 @@ config SCHED_INFO
 
 config SCHEDSTATS
 	bool "Collect scheduler statistics"
-	depends on DEBUG_KERNEL && PROC_FS
+	depends on DEBUG_KERNEL && PROC_FS && !SCHED_BFS
 	select SCHED_INFO
 	help
 	  If you say Y here, additional code will be inserted into the