Latest changes to poppler breaks build against Clang and libc++15

[Ilmari Lauhakangas]

On 12.1.2025 3.49, Etna - wrote:
> Hello all, attempting to build the latest checkout against Debian 12 on a self-compiled LLVM15, libc++15 and clang-15 returns the following error:
> 
> -----------
> /home/etna/Tmpdir/libreoffice/build/workdir/UnpackedTarball/poppler/poppler/Dict.cc:116:30: error: no member named 'sort' in namespace 'std::ranges'
>                  std::ranges::sort(that->entries, CmpDictEntry {});
>                  ~~~~~~~~~~~~~^
> /home/etna/Tmpdir/libreoffice/build/workdir/UnpackedTarball/poppler/poppler/Dict.cc:123:39: error: no member named 'lower_bound' in namespace 'std::ranges'
>          const auto pos = std::ranges::lower_bound(entries, key, std::less<> {}, &DictEntry::first);

Try this patch and let us know how it goes: 
https://gerrit.libreoffice.org/c/core/+/180026

Ilmari