hello,

Podofo 0.11.0 can't be built with gcc 13.2.0 on "UnionTech OS GNU/Linux 20".
Here are some advices to get it built. Tested ok.

1. Optionally remove "-Wno-unknown-warning-option" from CMAKE_CXX_FLAGS in CMakeLists.txt.
   This option is not reconized by gcc 13.2.0. But it only warns.

2. add "-fpermissive" to CMAKE_CXX_FLAGS in CMakeLists.txt.
   Or it will complains "__builtin_is_constant_evaluated is not delcared", introduced by source file "podofo/3rdparty/numerics/safe_conversions.h".

#define IsConstantEvaluated() (__builtin_is_constant_evaluated())

3. add "stdc++fs" to PODOFO_LIB_DEPENDS in CMakeLists.txt, to remove all undefined references to std::filesystem symbols.

list(APPEND PODOFO_LIB_DEPENDS "stdc++fs")

Thanks!