[llvm] [RISCV] Emit .note.gnu.property section when Zicfiss-based shadow stack is enabled (PR #127036)

[Ming-Yi Lai via llvm-commits]

mylai-mtk wrote:

> Is GNU_PROPERTY_RISCV_FEATURE_1_AND documented anywhere? When other targets introduced GNU_PROPERTY to compilers, there had been psABI documentation.

It's defined in PR riscv-non-isa/riscv-elf-psabi-doc#417 and GCC had already implemented it at https://github.com/gcc-mirror/gcc/blob/7cfb2c8839c4ccaaf7d66f446c4c0d040b710f18/gcc/config/riscv/riscv.cc#L10342

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Update: Address comments

https://github.com/llvm/llvm-project/pull/127036