[clang] [Clang] Add [[readnone, readonly, writeonly]] parameter attributes (PR #178429)

[Nikolas Klauser via cfe-commits]

philnik777 wrote:

@efriedma-quic Do you have an example of what such a definition would look like? Are you asking for something close to standardese here?

https://github.com/llvm/llvm-project/pull/178429