Performing C++ SOURCE FILE Test CMAKE_HAVE_LIBC_PTHREAD failed with the following output:
Change Dir: /home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make -f Makefile cmTC_688e0/fast && make[1]: Entering directory '/home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp'
/usr/bin/make  -f CMakeFiles/cmTC_688e0.dir/build.make CMakeFiles/cmTC_688e0.dir/build
make[2]: Entering directory '/home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_688e0.dir/src.cxx.o
/home/buildroot/autobuild/run/instance-2/output-1/host/bin/aarch64_be-linux-gnu-g++ --sysroot=/home/buildroot/autobuild/run/instance-2/output-1/host/aarch64_be-buildroot-linux-gnu/sysroot -DCMAKE_HAVE_LIBC_PTHREAD  -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g0 -D_FORTIFY_SOURCE=1   -DNDEBUG -o CMakeFiles/cmTC_688e0.dir/src.cxx.o -c /home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp/src.cxx
Linking CXX executable cmTC_688e0
/home/buildroot/autobuild/run/instance-2/output-1/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_688e0.dir/link.txt --verbose=1
/home/buildroot/autobuild/run/instance-2/output-1/host/bin/aarch64_be-linux-gnu-g++ --sysroot=/home/buildroot/autobuild/run/instance-2/output-1/host/aarch64_be-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g0 -D_FORTIFY_SOURCE=1   -DNDEBUG CMakeFiles/cmTC_688e0.dir/src.cxx.o -o cmTC_688e0 
CMakeFiles/cmTC_688e0.dir/src.cxx.o: In function `main':
src.cxx:(.text.startup+0x2c): undefined reference to `pthread_create'
src.cxx:(.text.startup+0x34): undefined reference to `pthread_detach'
src.cxx:(.text.startup+0x3c): undefined reference to `pthread_cancel'
src.cxx:(.text.startup+0x48): undefined reference to `pthread_join'
src.cxx:(.text.startup+0x58): undefined reference to `pthread_atfork'
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_688e0.dir/build.make:98: recipe for target 'cmTC_688e0' failed
make[2]: *** [cmTC_688e0] Error 1
make[2]: Leaving directory '/home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp'
Makefile:127: recipe for target 'cmTC_688e0/fast' failed
make[1]: *** [cmTC_688e0/fast] Error 2
make[1]: Leaving directory '/home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp'


Source file was:
#include <pthread.h>

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

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

  return 0;
}

Determining if the getpassphrase exist failed with the following output:
Change Dir: /home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make -f Makefile cmTC_91669/fast && make[1]: Entering directory '/home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp'
/usr/bin/make  -f CMakeFiles/cmTC_91669.dir/build.make CMakeFiles/cmTC_91669.dir/build
make[2]: Entering directory '/home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_91669.dir/CheckSymbolExists.cxx.o
/home/buildroot/autobuild/run/instance-2/output-1/host/bin/aarch64_be-linux-gnu-g++ --sysroot=/home/buildroot/autobuild/run/instance-2/output-1/host/aarch64_be-buildroot-linux-gnu/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g0 -D_FORTIFY_SOURCE=1   -DNDEBUG -o CMakeFiles/cmTC_91669.dir/CheckSymbolExists.cxx.o -c /home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx
/home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx: In function 'int main(int, char**)':
/home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx:8:19: error: 'getpassphrase' was not declared in this scope
   return ((int*)(&getpassphrase))[argc];
                   ^~~~~~~~~~~~~
CMakeFiles/cmTC_91669.dir/build.make:77: recipe for target 'CMakeFiles/cmTC_91669.dir/CheckSymbolExists.cxx.o' failed
make[2]: *** [CMakeFiles/cmTC_91669.dir/CheckSymbolExists.cxx.o] Error 1
make[2]: Leaving directory '/home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp'
Makefile:127: recipe for target 'cmTC_91669/fast' failed
make[1]: *** [cmTC_91669/fast] Error 2
make[1]: Leaving directory '/home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp'


File /home/buildroot/autobuild/run/instance-2/output-1/build/znc-1.8.2/CMakeFiles/CMakeTmp/CheckSymbolExists.cxx:
/* */
#include <stdlib.h>

int main(int argc, char** argv)
{
  (void)argv;
#ifndef getpassphrase
  return ((int*)(&getpassphrase))[argc];
#else
  (void)argc;
  return 0;
#endif
}