this adds kernel & libroot stack protector hooks. it uses /dev/random in userspace.
A configure option --enable-stack-protector is added to activate -fstack-protector
on selected system components (ATM apps, kits, servers).
Change-Id: If3a2920ba9aa0a85eaff4ba6778947f8c76ade31
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3895
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
