libember_slim build fails for c23

[babymotte]

When compiling ember-plus on linux, the build of libember_slim fails with the following error message:

[80/200] Building C object libember_slim/CMakeFiles/ember_slim-shared.dir/Source/ber.c.o
FAILED: libember_slim/CMakeFiles/ember_slim-shared.dir/Source/ber.c.o 
/usr/bin/cc -DLIBEMBER_DLL -DLIBEMBER_DLL_EXPORTS -Dember_slim_shared_EXPORTS  -O3 -DNDEBUG -flto=auto -fno-fat-lto-objects -fPIC -fvisibility=hidden -Wall -Wextra -Wunreachable-code -Wpedantic -Wno-long-long -MD -MT libember_slim/CMakeFiles/ember_slim-shared.dir/Source/ber.c.o -MF libember_slim/CMakeFiles/ember_slim-shared.dir/Source/ber.c.o.d -o libember_slim/CMakeFiles/ember_slim-shared.dir/Source/ber.c.o -c /home/mbachmann/code/ember/ember-plus/libember_slim/Source/ber.c
In file included from /home/mbachmann/code/ember/ember-plus/libember_slim/Source/ber.h:13,
                 from /home/mbachmann/code/ember/ember-plus/libember_slim/Source/ber.c:12:
/home/mbachmann/code/ember/ember-plus/libember_slim/Source/bertypes.h:83:13: error: ‘bool’ cannot be defined via ‘typedef’
   83 | typedef int bool;
      |             ^~~~
/home/mbachmann/code/ember/ember-plus/libember_slim/Source/bertypes.h:83:13: note: ‘bool’ is a keyword with ‘-std=c23’ onwards
/home/mbachmann/code/ember/ember-plus/libember_slim/Source/bertypes.h:83:1: warning: useless type name in empty declaration
   83 | typedef int bool;
      | ^~~~~~~
[103/200] Building CXX object libember/CMakeFiles/ember-shared.dir/Source/glow/GlowStreamEntry.cpp.o
ninja: build stopped: subcommand failed.

The build command I used was:

cmake -G Ninja -B "./build" -DCMAKE_BUILD_TYPE=Release
cmake --build "./build" --config "Release"

cmake --version:

cmake version 4.1.0

CMake suite maintained and supported by Kitware (kitware.com/cmake).

ninja --version:

1.12.1

cc --version --version:

cc (GCC) 15.2.1 20250813
Copyright (C) 2025 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.