[Bug ipa/114930] ICE in fld_incomplete_type_of when building libwebp with -std=c23 -flto

[sjames at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114930

--- Comment #1 from Sam James <sjames at gcc dot gnu.org> ---
reduced:
```
typedef struct WebPPicture WebPPicture;
typedef int (*WebPProgressHook)(const WebPPicture *);
WebPProgressHook progress_hook;
struct WebPPicture {
} WebPGetColorPalette(const struct WebPPicture *);
```