x86: add a simple backtrace test module

During the work on the x86 32 and 64 bit backtrace code I found it useful
to have a simple test module to test a process and irq context backtrace.
Since the existing backtrace code was buggy, I figure it might be useful
to have such a test module in the kernel so that maybe we can even
detect such bugs earlier..

[ mingo@elte.hu: build fix ]

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index f535b9b..aa56e63 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -506,6 +506,18 @@
 
 	  Say N if you are unsure.
 
+config BACKTRACE_SELF_TEST
+	tristate "Self test for the backtrace code"
+	depends on DEBUG_KERNEL
+	default n
+	help
+	  This option provides a kernel module that can be used to test
+	  the kernel stack backtrace code. This option is not useful
+	  for distributions or general kernels, but only for kernel
+	  developers working on architecture code.
+
+	  Say N if you are unsure.
+
 config LKDTM
 	tristate "Linux Kernel Dump Test Tool Module"
 	depends on DEBUG_KERNEL