[clang] [clang][wasm] Replace the target integer add saturate intrinsics with the equivalent generic `__builtin_elementwise_add_sat` intrinsics (PR #109269)

[Thomas Lively via cfe-commits]

https://github.com/tlively approved this pull request.

LGTM. FWIW, I'm not aware of any special reason why `wasm_sub_sat` should be any different.

https://github.com/llvm/llvm-project/pull/109269