ARM: initial stack protector (-fstack-protector) support

This is the very basic stuff without the changing canary upon
task switch yet.  Just the Kconfig option and a constant canary
value initialized at boot time.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 64ba313..ddf6da1 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -34,6 +34,10 @@
 KBUILD_CFLAGS	+=-fno-omit-frame-pointer -mapcs -mno-sched-prolog
 endif
 
+ifeq ($(CONFIG_CC_STACKPROTECTOR),y)
+KBUILD_CFLAGS	+=-fstack-protector
+endif
+
 ifeq ($(CONFIG_CPU_BIG_ENDIAN),y)
 KBUILD_CPPFLAGS	+= -mbig-endian
 AS		+= -EB