[clang] Fix INF/NAN warning. (PR #80290)

[Aaron Ballman via cfe-commits]

================
@@ -3288,7 +3288,7 @@ void Preprocessor::HandleIfdefDirective(Token &Result,
     return;
   }
 
-  emitMacroExpansionWarnings(MacroNameTok);
+  emitMacroExpansionWarnings(MacroNameTok, true);
----------------
AaronBallman wrote:

```suggestion
  emitMacroExpansionWarnings(MacroNameTok, /*IsIfnDef=*/true);
```

https://github.com/llvm/llvm-project/pull/80290