Enable shadow stack from .note.gnu.property

[SuHo-llrr]

reference from llvm-project commit llvm/llvm-project#77414

1. Parse .note.gun.property to check Zicfiss/Zicfilp properties
2. If Zicfiss on, we should allocate SS(Shadow stack) page with PROT_WRITE
3. We should allow allocate no-read page when SS page allocating

Some tasks require discussion:

• What should the default shadow stack size be?
• How to allow page allocation only for write-only pages?

• Checking instruction with epc address? (Maybe this is more in line with hardware behavior.)
• Checking ELF enable shstk flag?

[aswaterman]

This seems like a very heavyweight addition with only minor incremental value. I would prefer that pk instead just declare no support for this extension, instead unconditionally setting the various control bits so that SS/LP are disabled in this context.

cc @ved-rivos