[clang] [X86] Define __APX_F__ when APX is enabled. (PR #88343)

[Shengchen Kan via cfe-commits]

================
@@ -954,6 +954,8 @@ void X86TargetInfo::getTargetDefines(const LangOptions &Opts,
     Builder.defineMacro("__CCMP__");
   if (HasCF)
     Builder.defineMacro("__CF__");
+  if (HasEGPR && HasPush2Pop2 && HasPPX && HasNDD)
----------------
KanRobert wrote:

Add comment
`Condition here is aligned with the feature set of mapxf in Options.td`

https://github.com/llvm/llvm-project/pull/88343