[clang] fix bug that undefined internal is a warning only for -pedantic-errors (PR #98016)

[Aaron Ballman via cfe-commits]

================
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s -pedantic-errors
+
+// expected-no-diagnostics
+
+static int f(void);
+
+int main(void)
+{
+    int x = sizeof f();
----------------
AaronBallman wrote:

```suggestion
    int x = sizeof(f);
```

https://github.com/llvm/llvm-project/pull/98016