Performing C SOURCE FILE Test CMAKE_HAVE_LIBC_PTHREAD failed with the following output:
Change Dir: /home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_1677e/fast && make[1]: Entering directory '/home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_1677e.dir/build.make CMakeFiles/cmTC_1677e.dir/build
make[2]: Entering directory '/home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_1677e.dir/src.c.o
/home/buildroot/autobuild/instance-3/output-1/host/bin/riscv64-linux-gcc --sysroot=/home/buildroot/autobuild/instance-3/output-1/host/riscv64-buildroot-linux-gnu/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g2 -DCMAKE_HAVE_LIBC_PTHREAD   -o CMakeFiles/cmTC_1677e.dir/src.c.o   -c /home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp/src.c
Linking C executable cmTC_1677e
/home/buildroot/autobuild/instance-3/output-1/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_1677e.dir/link.txt --verbose=1
/home/buildroot/autobuild/instance-3/output-1/host/bin/riscv64-linux-gcc --sysroot=/home/buildroot/autobuild/instance-3/output-1/host/riscv64-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g2 -DCMAKE_HAVE_LIBC_PTHREAD    CMakeFiles/cmTC_1677e.dir/src.c.o  -o cmTC_1677e 
/home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/bin/../lib/gcc/riscv64-buildroot-linux-gnu/8.3.0/../../../../riscv64-buildroot-linux-gnu/bin/ld: CMakeFiles/cmTC_1677e.dir/src.c.o: in function `main':
/home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp/src.c:11: undefined reference to `pthread_create'
/home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/bin/../lib/gcc/riscv64-buildroot-linux-gnu/8.3.0/../../../../riscv64-buildroot-linux-gnu/bin/ld: /home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp/src.c:12: undefined reference to `pthread_detach'
/home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/bin/../lib/gcc/riscv64-buildroot-linux-gnu/8.3.0/../../../../riscv64-buildroot-linux-gnu/bin/ld: /home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp/src.c:13: undefined reference to `pthread_join'
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_1677e.dir/build.make:86: recipe for target 'cmTC_1677e' failed
make[2]: *** [cmTC_1677e] Error 1
make[2]: Leaving directory '/home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp'
Makefile:121: recipe for target 'cmTC_1677e/fast' failed
make[1]: *** [cmTC_1677e/fast] Error 2
make[1]: Leaving directory '/home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/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/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_cdac1/fast && make[1]: Entering directory '/home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_cdac1.dir/build.make CMakeFiles/cmTC_cdac1.dir/build
make[2]: Entering directory '/home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_cdac1.dir/CheckFunctionExists.c.o
/home/buildroot/autobuild/instance-3/output-1/host/bin/riscv64-linux-gcc --sysroot=/home/buildroot/autobuild/instance-3/output-1/host/riscv64-buildroot-linux-gnu/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g2 -DCHECK_FUNCTION_EXISTS=pthread_create   -o CMakeFiles/cmTC_cdac1.dir/CheckFunctionExists.c.o   -c /home/buildroot/autobuild/instance-3/output-1/host/share/cmake-3.15/Modules/CheckFunctionExists.c
Linking C executable cmTC_cdac1
/home/buildroot/autobuild/instance-3/output-1/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_cdac1.dir/link.txt --verbose=1
/home/buildroot/autobuild/instance-3/output-1/host/bin/riscv64-linux-gcc --sysroot=/home/buildroot/autobuild/instance-3/output-1/host/riscv64-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g2 -DCHECK_FUNCTION_EXISTS=pthread_create    CMakeFiles/cmTC_cdac1.dir/CheckFunctionExists.c.o  -o cmTC_cdac1 -lpthreads 
/home/buildroot/autobuild/instance-3/output-1/host/opt/ext-toolchain/bin/../lib/gcc/riscv64-buildroot-linux-gnu/8.3.0/../../../../riscv64-buildroot-linux-gnu/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_cdac1.dir/build.make:86: recipe for target 'cmTC_cdac1' failed
make[2]: *** [cmTC_cdac1] Error 1
make[2]: Leaving directory '/home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp'
Makefile:121: recipe for target 'cmTC_cdac1/fast' failed
make[1]: *** [cmTC_cdac1/fast] Error 2
make[1]: Leaving directory '/home/buildroot/autobuild/instance-3/output-1/build/domoticz-2020.1/CMakeFiles/CMakeTmp'