CMakeError.log, building process-cpp 2017-04-12

Determining if the pthread_create exist failed with the following output:
Change Dir: /tmp/yaourt-tmp-josh/aur-process-cpp/src/process-cpp-3.0.1/build/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_fc66f/fast"
/usr/bin/make -f CMakeFiles/cmTC_fc66f.dir/build.make CMakeFiles/cmTC_fc66f.dir/build
make[1]: Entering directory '/tmp/yaourt-tmp-josh/aur-process-cpp/src/process-cpp-3.0.1/build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_fc66f.dir/CheckSymbolExists.c.o
/usr/bin/cc    -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong    -o CMakeFiles/cmTC_fc66f.dir/CheckSymbolExists.c.o   -c /tmp/yaourt-tmp-josh/aur-process-cpp/src/process-cpp-3.0.1/build/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_fc66f
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_fc66f.dir/link.txt --verbose=1
/usr/bin/cc  -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong   -Wl,-O1,--sort-common,--as-needed,-z,relro  CMakeFiles/cmTC_fc66f.dir/CheckSymbolExists.c.o  -o cmTC_fc66f -rdynamic
CMakeFiles/cmTC_fc66f.dir/CheckSymbolExists.c.o: In function `main':
CheckSymbolExists.c:(.text.startup+0x6): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
make[1]: *** [CMakeFiles/cmTC_fc66f.dir/build.make:98: cmTC_fc66f] Error 1
make[1]: Leaving directory '/tmp/yaourt-tmp-josh/aur-process-cpp/src/process-cpp-3.0.1/build/CMakeFiles/CMakeTmp'
make: *** [Makefile:126: cmTC_fc66f/fast] Error 2

File /tmp/yaourt-tmp-josh/aur-process-cpp/src/process-cpp-3.0.1/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/yaourt-tmp-josh/aur-process-cpp/src/process-cpp-3.0.1/build/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_5c953/fast"
/usr/bin/make -f CMakeFiles/cmTC_5c953.dir/build.make CMakeFiles/cmTC_5c953.dir/build
make[1]: Entering directory '/tmp/yaourt-tmp-josh/aur-process-cpp/src/process-cpp-3.0.1/build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_5c953.dir/CheckFunctionExists.c.o
/usr/bin/cc    -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -DCHECK_FUNCTION_EXISTS=pthread_create   -o CMakeFiles/cmTC_5c953.dir/CheckFunctionExists.c.o   -c /usr/share/cmake-3.7/Modules/CheckFunctionExists.c
Linking C executable cmTC_5c953
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_5c953.dir/link.txt --verbose=1
/usr/bin/cc  -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -DCHECK_FUNCTION_EXISTS=pthread_create  -Wl,-O1,--sort-common,--as-needed,-z,relro  CMakeFiles/cmTC_5c953.dir/CheckFunctionExists.c.o  -o cmTC_5c953 -rdynamic -lpthreads
/usr/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
make[1]: *** [CMakeFiles/cmTC_5c953.dir/build.make:98: cmTC_5c953] Error 1
make[1]: Leaving directory '/tmp/yaourt-tmp-josh/aur-process-cpp/src/process-cpp-3.0.1/build/CMakeFiles/CMakeTmp'
make: *** [Makefile:126: cmTC_5c953/fast] Error 2