[clang] [clang] Fix incorrect uses header-name lexing rules when #include is followed by an empty macro expansion (PR #225451)

[Yihan Wang via cfe-commits]

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yronglin wrote:

The diagnose would be:

```
./main.cpp:10:14: warning: extra tokens after semicolon in 'import' directive [-Wextra-tokens]
   10 | import EMPTY "foo.h";
      |              ^
      |              //
```

IIUC, `EMPTY` would be traited as a identifier. But IMO, this look wired.

https://github.com/llvm/llvm-project/pull/225451