lib: consolidate DEBUG_STACK_USAGE option

Most arches define CONFIG_DEBUG_STACK_USAGE exactly the same way.  Move it
to lib/Kconfig.debug so each arch doesn't have to define it.  This
obviously makes the option generic, but that's fine because the config is
already used in generic code.

It's not obvious to me that sysrq-P actually does anything caution by
keeping the most inclusive wording.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Richard Weinberger <richard@nod.at>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Chen Liqin <liqin.chen@sunplusct.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 09596e0..28afa4c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -670,6 +670,15 @@
 	bool
 	depends on STACKTRACE_SUPPORT
 
+config DEBUG_STACK_USAGE
+	bool "Stack utilization instrumentation"
+	depends on DEBUG_KERNEL
+	help
+	  Enables the display of the minimum amount of free stack which each
+	  task has ever had available in the sysrq-T and sysrq-P debug output.
+
+	  This option will slow down process creation somewhat.
+
 config DEBUG_KOBJECT
 	bool "kobject debugging"
 	depends on DEBUG_KERNEL