softlockup: make DETECT_HUNG_TASK default depend on DETECT_SOFTLOCKUP

Don't offer a default-y option when the user has turned off
CONFIG_DETECT_SOFTLOCKUP already.

Do offer it as 'y' only if DETECT_SOFTLOCKUP is on already.

This makes it match previous behavior - where the hung-task check was
embedded i CONFIG_DETECT_SOFTLOCKUP code.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

lib/Kconfig.debug

@@ -189,7 +189,7 @@ config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 config DETECT_HUNG_TASK
 	bool "Detect Hung Tasks"
 	depends on DEBUG_KERNEL
-	default y
+	default DETECT_SOFTLOCKUP
 	help
 	  Say Y here to enable the kernel to detect "hung tasks",
 	  which are bugs that cause the task to be stuck in