Determining if the pthread_create exist failed with the following output:
Change Dir: /tmp/umr/build/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/gmake" "cmTC_1a689/fast"
/usr/bin/gmake -f CMakeFiles/cmTC_1a689.dir/build.make CMakeFiles/cmTC_1a689.dir/build
gmake[1]: Entering directory '/tmp/umr/build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_1a689.dir/CheckSymbolExists.c.o
/usr/bin/cc    -o CMakeFiles/cmTC_1a689.dir/CheckSymbolExists.c.o   -c /tmp/umr/build/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_1a689
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_1a689.dir/link.txt --verbose=1
/usr/bin/cc      -rdynamic CMakeFiles/cmTC_1a689.dir/CheckSymbolExists.c.o  -o cmTC_1a689 
CMakeFiles/cmTC_1a689.dir/CheckSymbolExists.c.o: In function `main':
CheckSymbolExists.c:(.text+0x16): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
gmake[1]: *** [CMakeFiles/cmTC_1a689.dir/build.make:98: cmTC_1a689] Error 1
gmake[1]: Leaving directory '/tmp/umr/build/CMakeFiles/CMakeTmp'
gmake: *** [Makefile:126: cmTC_1a689/fast] Error 2

File /tmp/umr/build/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: /tmp/umr/build/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/gmake" "cmTC_88cc8/fast"
/usr/bin/gmake -f CMakeFiles/cmTC_88cc8.dir/build.make CMakeFiles/cmTC_88cc8.dir/build
gmake[1]: Entering directory '/tmp/umr/build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_88cc8.dir/CheckFunctionExists.c.o
/usr/bin/cc   -DCHECK_FUNCTION_EXISTS=pthread_create   -o CMakeFiles/cmTC_88cc8.dir/CheckFunctionExists.c.o   -c /usr/share/cmake-3.8/Modules/CheckFunctionExists.c
Linking C executable cmTC_88cc8
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_88cc8.dir/link.txt --verbose=1
/usr/bin/cc  -DCHECK_FUNCTION_EXISTS=pthread_create    -rdynamic CMakeFiles/cmTC_88cc8.dir/CheckFunctionExists.c.o  -o cmTC_88cc8 -lpthreads 
/usr/lib64/gcc/x86_64-slackware-linux/7.1.0/../../../../x86_64-slackware-linux/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
gmake[1]: *** [CMakeFiles/cmTC_88cc8.dir/build.make:98: cmTC_88cc8] Error 1
gmake[1]: Leaving directory '/tmp/umr/build/CMakeFiles/CMakeTmp'
gmake: *** [Makefile:126: cmTC_88cc8/fast] Error 2