kbuild/extable: Hook up sortextable into the build system.

Define a config variable BUILDTIME_EXTABLE_SORT to control build time
sorting of the kernel's exception table.

Patch Makefile to do the sorting when BUILDTIME_EXTABLE_SORT is
selected.

Signed-off-by: David Daney <david.daney@cavium.com>
Link: http://lkml.kernel.org/r/1334872799-14589-4-git-send-email-ddaney.cavm@gmail.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/init/Kconfig b/init/Kconfig
index 6cfd71d..92a1296 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -27,6 +27,9 @@
 	bool
 	depends on HAVE_IRQ_WORK
 
+config BUILDTIME_EXTABLE_SORT
+	bool
+
 menu "General setup"
 
 config EXPERIMENTAL