Determining if the include file pthread.h exists failed with the following output:
Change Dir: /home/buildroot/autobuild/run/instance-0/output-1/build/zxing-cpp-1.4.0/buildroot-build/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make -f Makefile cmTC_d1b5c/fast && make[1]: Entering directory '/home/buildroot/autobuild/run/instance-0/output-1/build/zxing-cpp-1.4.0/buildroot-build/CMakeFiles/CMakeTmp'
/usr/bin/make  -f CMakeFiles/cmTC_d1b5c.dir/build.make CMakeFiles/cmTC_d1b5c.dir/build
make[2]: Entering directory '/home/buildroot/autobuild/run/instance-0/output-1/build/zxing-cpp-1.4.0/buildroot-build/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_d1b5c.dir/CheckIncludeFile.cxx.o
/home/buildroot/autobuild/run/instance-0/output-1/host/bin/arm-linux-g++ --sysroot=/home/buildroot/autobuild/run/instance-0/output-1/host/arm-buildroot-linux-uclibcgnueabihf/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -g0   -DNDEBUG -std=c++17 -o CMakeFiles/cmTC_d1b5c.dir/CheckIncludeFile.cxx.o -c /home/buildroot/autobuild/run/instance-0/output-1/build/zxing-cpp-1.4.0/buildroot-build/CMakeFiles/CMakeTmp/CheckIncludeFile.cxx
/home/buildroot/autobuild/run/instance-0/output-1/build/zxing-cpp-1.4.0/buildroot-build/CMakeFiles/CMakeTmp/CheckIncludeFile.cxx:1:10: fatal error: pthread.h: No such file or directory
    1 | #include <pthread.h>
      |          ^~~~~~~~~~~
compilation terminated.
CMakeFiles/cmTC_d1b5c.dir/build.make:77: recipe for target 'CMakeFiles/cmTC_d1b5c.dir/CheckIncludeFile.cxx.o' failed
make[2]: *** [CMakeFiles/cmTC_d1b5c.dir/CheckIncludeFile.cxx.o] Error 1
make[2]: Leaving directory '/home/buildroot/autobuild/run/instance-0/output-1/build/zxing-cpp-1.4.0/buildroot-build/CMakeFiles/CMakeTmp'
Makefile:127: recipe for target 'cmTC_d1b5c/fast' failed
make[1]: *** [cmTC_d1b5c/fast] Error 2
make[1]: Leaving directory '/home/buildroot/autobuild/run/instance-0/output-1/build/zxing-cpp-1.4.0/buildroot-build/CMakeFiles/CMakeTmp'