[clang] [CLANG][AArch64] Add the modal 8 bit floating-point scalar type (PR #97277)

[Paul Walker via cfe-commits]

================
@@ -325,6 +325,8 @@ class DeclSpec {
 #define HLSL_INTANGIBLE_TYPE(Name, Id, SingletonId)                            \
   static const TST TST_##Name = clang::TST_##Name;
 #include "clang/Basic/HLSLIntangibleTypes.def"
+  // AARCH64_OPAQUE_TYPE
+  static const TST TST_ArmMFloat8_t = clang::TST_ArmMFloat8_t;
----------------
paulwalker-arm wrote:

My knowledge here is not great but the comment suggests this is for enumerations and constants? but given the types are opaque I'm wondering how like these will be.

There's no C/C++ literal support for fp8 data and any conversation would be dependent on the value of FPMR and so I'm not sure what level of support we should be adding. 

https://github.com/llvm/llvm-project/pull/97277