BACKPORT: 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.

The Android backport only adds INIT_STACK_NONE, as GCC plugins are
unavailable in the Android 4.14 tree.

Change-Id: Ic11cb574d2b447e30b0d93977a6707b53744e1cf
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
(cherry picked from commit 9f671e58159adea641f76c56d1f0bbdcb3c524ff)
Bug: 133428616
Signed-off-by: Alexander Potapenko <glider@google.com>