lockup_detector: Introduce CONFIG_HARDLOCKUP_DETECTOR

This new config is deemed to simplify even more the lockup detector
dependencies and can make it easier to bring a smooth sorting
between archs that support the new generic lockup detector and those
that still have their own, especially for those that are in the
middle of this migration.

Instead of checking whether we have CONFIG_LOCKUP_DETECTOR +
CONFIG_PERF_EVENTS_NMI each time an arch wants to know if it needs
to build its own lockup detector, take a shortcut with this new
config. It is enabled only if the hardlockup detection part of
the whole lockup detector is on.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 3a18b0b..e65e47d 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -174,6 +174,9 @@
 	  generate interrupts and kick the watchdog task every 10-12 seconds.
 	  An NMI is generated every 60 seconds or so to check for hardlockups.
 
+config HARDLOCKUP_DETECTOR
+	def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI
+
 config BOOTPARAM_SOFTLOCKUP_PANIC
 	bool "Panic (Reboot) On Soft Lockups"
 	depends on LOCKUP_DETECTOR