[clang] [clang][PAC] add support for options parameter to __ptrauth (PR #136828)

[Erich Keane via cfe-commits]

================
@@ -65,6 +65,17 @@ enum class PointerAuthenticationMode : unsigned {
   SignAndAuth
 };
 
+static constexpr llvm::StringLiteral PointerAuthenticationOptionStrip = "strip";
----------------
erichkeane wrote:

I'd suggest doing a string-switch on it, then storing an enum in the AST.  We can then print it/whatever on the way out.  But a pair of conversion functions is typically all you should need.  Though, it doesn't seem that these are leaving the `handle` function anyway, so IDK.

Either way, LangOpts is a little bit of an odd place for this to live.

https://github.com/llvm/llvm-project/pull/136828