Performing C SOURCE FILE Test CMAKE_HAVE_LIBC_PTHREAD failed with the following output:
Change Dir: /home/buildroot/autobuild/run/instance-1/output-1/build/netopeer2-1.1.53/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_68214/fast && make[1]: Entering directory `/home/buildroot/autobuild/run/instance-1/output-1/build/netopeer2-1.1.53/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_68214.dir/build.make CMakeFiles/cmTC_68214.dir/build
make[2]: Entering directory `/home/buildroot/autobuild/run/instance-1/output-1/build/netopeer2-1.1.53/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_68214.dir/src.c.o
/home/buildroot/autobuild/run/instance-1/output-1/host/bin/s390x-buildroot-linux-gnu-gcc --sysroot=/home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot -D_GNU_SOURCE -D_POSIX_C_SOURCE=200809L -D__BSD_VISIBLE=1  -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -DCMAKE_HAVE_LIBC_PTHREAD  -DNDEBUG   -o CMakeFiles/cmTC_68214.dir/src.c.o   -c /home/buildroot/autobuild/run/instance-1/output-1/build/netopeer2-1.1.53/CMakeFiles/CMakeTmp/src.c
Linking C executable cmTC_68214
/home/buildroot/autobuild/run/instance-1/output-1/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_68214.dir/link.txt --verbose=1
/home/buildroot/autobuild/run/instance-1/output-1/host/bin/s390x-buildroot-linux-gnu-gcc --sysroot=/home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -DCMAKE_HAVE_LIBC_PTHREAD  -DNDEBUG    CMakeFiles/cmTC_68214.dir/src.c.o  -o cmTC_68214 /home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot/usr/lib/libssl.so /home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot/usr/lib/libcrypto.so /home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot/usr/lib/libssh.so /home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot/usr/lib/libnetconf2.so 
/home/buildroot/autobuild/run/instance-1/output-1/host/lib/gcc/s390x-buildroot-linux-gnu/9.3.0/../../../../s390x-buildroot-linux-gnu/bin/ld: CMakeFiles/cmTC_68214.dir/src.c.o: undefined reference to symbol 'pthread_create@@GLIBC_2.2'
/home/buildroot/autobuild/run/instance-1/output-1/host/lib/gcc/s390x-buildroot-linux-gnu/9.3.0/../../../../s390x-buildroot-linux-gnu/bin/ld: /home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot/lib64/libpthread.so.0: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
make[2]: *** [cmTC_68214] Error 1
make[2]: Leaving directory `/home/buildroot/autobuild/run/instance-1/output-1/build/netopeer2-1.1.53/CMakeFiles/CMakeTmp'
make[1]: *** [cmTC_68214/fast] Error 2
make[1]: Leaving directory `/home/buildroot/autobuild/run/instance-1/output-1/build/netopeer2-1.1.53/CMakeFiles/CMakeTmp'


Source file was:
#include <pthread.h>

void* test_func(void* data)
{
  return data;
}

int main(void)
{
  pthread_t thread;
  pthread_create(&thread, NULL, test_func, NULL);
  pthread_detach(thread);
  pthread_join(thread, NULL);
  pthread_atfork(NULL, NULL, NULL);
  pthread_exit(NULL);

  return 0;
}

Determining if the function pthread_create exists in the pthreads failed with the following output:
Change Dir: /home/buildroot/autobuild/run/instance-1/output-1/build/netopeer2-1.1.53/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_59422/fast && make[1]: Entering directory `/home/buildroot/autobuild/run/instance-1/output-1/build/netopeer2-1.1.53/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_59422.dir/build.make CMakeFiles/cmTC_59422.dir/build
make[2]: Entering directory `/home/buildroot/autobuild/run/instance-1/output-1/build/netopeer2-1.1.53/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_59422.dir/CheckFunctionExists.c.o
/home/buildroot/autobuild/run/instance-1/output-1/host/bin/s390x-buildroot-linux-gnu-gcc --sysroot=/home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot -D_GNU_SOURCE -D_POSIX_C_SOURCE=200809L -D__BSD_VISIBLE=1  -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG   -o CMakeFiles/cmTC_59422.dir/CheckFunctionExists.c.o   -c /home/buildroot/autobuild/run/instance-1/output-1/host/share/cmake-3.15/Modules/CheckFunctionExists.c
Linking C executable cmTC_59422
/home/buildroot/autobuild/run/instance-1/output-1/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_59422.dir/link.txt --verbose=1
/home/buildroot/autobuild/run/instance-1/output-1/host/bin/s390x-buildroot-linux-gnu-gcc --sysroot=/home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG    CMakeFiles/cmTC_59422.dir/CheckFunctionExists.c.o  -o cmTC_59422 -lpthreads /home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot/usr/lib/libssl.so /home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot/usr/lib/libcrypto.so /home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot/usr/lib/libssh.so /home/buildroot/autobuild/run/instance-1/output-1/host/s390x-buildroot-linux-gnu/sysroot/usr/lib/libnetconf2.so 
/home/buildroot/autobuild/run/instance-1/output-1/host/lib/gcc/s390x-buildroot-linux-gnu/9.3.0/../../../../s390x-buildroot-linux-gnu/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
make[2]: *** [cmTC_59422] Error 1
make[2]: Leaving directory `/home/buildroot/autobuild/run/instance-1/output-1/build/netopeer2-1.1.53/CMakeFiles/CMakeTmp'
make[1]: *** [cmTC_59422/fast] Error 2
make[1]: Leaving directory `/home/buildroot/autobuild/run/instance-1/output-1/build/netopeer2-1.1.53/CMakeFiles/CMakeTmp'