security: Create "kernel hardening" config area

Right now kernel hardening options are scattered around various Kconfig
files. This can be a central place to collect these kinds of options
going forward. This is initially populated with the memory initialization
options from the gcc-plugins.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/security/Kconfig b/security/Kconfig
index 1d6463f..7aec8d0 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -249,5 +249,7 @@
 
 	  If unsure, leave this as the default.
 
+source "security/Kconfig.hardening"
+
 endmenu