Determining if the pthread_create exist failed with the following output:
Change Dir: /home/usertest/poissonsolver/example/test/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/gmake" "cmTC_0ed47/fast"
gmake: Warning: File `Makefile' has modification time 11 s in the future
/usr/bin/gmake -f CMakeFiles/cmTC_0ed47.dir/build.make CMakeFiles/cmTC_0ed47.dir/build
gmake[1]: Entering directory `/home/usertest/poissonsolver/example/test/CMakeFiles/CMakeTmp'
gmake[1]: Warning: File `CMakeFiles/cmTC_0ed47.dir/flags.make' has modification time 11 s in the future
Building C object CMakeFiles/cmTC_0ed47.dir/CheckSymbolExists.c.o
/usr/bin/cc   -fPIC    -o CMakeFiles/cmTC_0ed47.dir/CheckSymbolExists.c.o   -c /home/usertest/poissonsolver/example/test/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_0ed47
/apps/tools/cmake-3.10.3/bin/cmake -E cmake_link_script CMakeFiles/cmTC_0ed47.dir/link.txt --verbose=1
/usr/bin/cc -fPIC     -rdynamic CMakeFiles/cmTC_0ed47.dir/CheckSymbolExists.c.o  -o cmTC_0ed47 
CMakeFiles/cmTC_0ed47.dir/CheckSymbolExists.c.o: In function `main':
CheckSymbolExists.c:(.text+0x1b): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
gmake[1]: *** [cmTC_0ed47] Error 1
gmake[1]: Leaving directory `/home/usertest/poissonsolver/example/test/CMakeFiles/CMakeTmp'
gmake: *** [cmTC_0ed47/fast] Error 2

File /home/usertest/poissonsolver/example/test/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <pthread.h>

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

Determining if the function pthread_create exists in the pthreads failed with the following output:
Change Dir: /home/usertest/poissonsolver/example/test/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/gmake" "cmTC_619d2/fast"
gmake: Warning: File `Makefile' has modification time 11 s in the future
/usr/bin/gmake -f CMakeFiles/cmTC_619d2.dir/build.make CMakeFiles/cmTC_619d2.dir/build
gmake[1]: Entering directory `/home/usertest/poissonsolver/example/test/CMakeFiles/CMakeTmp'
gmake[1]: Warning: File `CMakeFiles/cmTC_619d2.dir/flags.make' has modification time 11 s in the future
Building C object CMakeFiles/cmTC_619d2.dir/CheckFunctionExists.c.o
/usr/bin/cc   -fPIC -DCHECK_FUNCTION_EXISTS=pthread_create   -o CMakeFiles/cmTC_619d2.dir/CheckFunctionExists.c.o   -c /apps/tools/cmake-3.10.3/share/cmake-3.10/Modules/CheckFunctionExists.c
Linking C executable cmTC_619d2
/apps/tools/cmake-3.10.3/bin/cmake -E cmake_link_script CMakeFiles/cmTC_619d2.dir/link.txt --verbose=1
/usr/bin/cc -fPIC -DCHECK_FUNCTION_EXISTS=pthread_create    -rdynamic CMakeFiles/cmTC_619d2.dir/CheckFunctionExists.c.o  -o cmTC_619d2 -lpthreads 
/usr/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
gmake[1]: *** [cmTC_619d2] Error 1
gmake[1]: Leaving directory `/home/usertest/poissonsolver/example/test/CMakeFiles/CMakeTmp'
gmake: *** [cmTC_619d2/fast] Error 2