[IR] make stack-protector-guard-* flags into module attrs

D88631 added initial support for:

- -mstack-protector-guard=
- -mstack-protector-guard-reg=
- -mstack-protector-guard-offset=

flags, and D100919 extended these to AArch64. Unfortunately, these flags
aren't retained for LTO. Make them module attributes rather than
TargetOptions.

Link: https://github.com/ClangBuiltLinux/linux/issues/1378

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D102742