Determining if the pthread_create exist failed with the following output:
Change Dir: /home/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_83e37/fast"
make[1]: Entering directory '/home/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_83e37.dir/build.make CMakeFiles/cmTC_83e37.dir/build
make[2]: Entering directory '/home/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_83e37.dir/CheckSymbolExists.c.o
/home/peko/autobuild/instance-0/output/host/bin/arm-none-linux-gnueabi-gcc  --sysroot=/home/peko/autobuild/instance-0/output/host/arm-buildroot-linux-gnueabi/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG   -o CMakeFiles/cmTC_83e37.dir/CheckSymbolExists.c.o   -c /home/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_83e37
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_83e37.dir/link.txt --verbose=1
/home/peko/autobuild/instance-0/output/host/bin/arm-none-linux-gnueabi-gcc  --sysroot=/home/peko/autobuild/instance-0/output/host/arm-buildroot-linux-gnueabi/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG    CMakeFiles/cmTC_83e37.dir/CheckSymbolExists.c.o  -o cmTC_83e37 -rdynamic 
CMakeFiles/cmTC_83e37.dir/CheckSymbolExists.c.o: In function `main':
CheckSymbolExists.c:(.text.startup+0x8): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_83e37.dir/build.make:97: recipe for target 'cmTC_83e37' failed
make[2]: *** [cmTC_83e37] Error 1
make[2]: Leaving directory '/home/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/CMakeFiles/CMakeTmp'
Makefile:126: recipe for target 'cmTC_83e37/fast' failed
make[1]: *** [cmTC_83e37/fast] Error 2
make[1]: Leaving directory '/home/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/CMakeFiles/CMakeTmp'

File /home/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/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/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_ddb8d/fast"
make[1]: Entering directory '/home/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_ddb8d.dir/build.make CMakeFiles/cmTC_ddb8d.dir/build
make[2]: Entering directory '/home/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_ddb8d.dir/CheckFunctionExists.c.o
/home/peko/autobuild/instance-0/output/host/bin/arm-none-linux-gnueabi-gcc  --sysroot=/home/peko/autobuild/instance-0/output/host/arm-buildroot-linux-gnueabi/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG   -o CMakeFiles/cmTC_ddb8d.dir/CheckFunctionExists.c.o   -c /usr/share/cmake-3.7/Modules/CheckFunctionExists.c
Linking C executable cmTC_ddb8d
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_ddb8d.dir/link.txt --verbose=1
/home/peko/autobuild/instance-0/output/host/bin/arm-none-linux-gnueabi-gcc  --sysroot=/home/peko/autobuild/instance-0/output/host/arm-buildroot-linux-gnueabi/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG    CMakeFiles/cmTC_ddb8d.dir/CheckFunctionExists.c.o  -o cmTC_ddb8d -rdynamic -lpthreads 
/home/peko/autobuild/instance-0/output/host/opt/ext-toolchain/bin/../lib/gcc/arm-none-linux-gnueabi/4.8.3/../../../../arm-none-linux-gnueabi/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_ddb8d.dir/build.make:97: recipe for target 'cmTC_ddb8d' failed
make[2]: *** [cmTC_ddb8d] Error 1
make[2]: Leaving directory '/home/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/CMakeFiles/CMakeTmp'
Makefile:126: recipe for target 'cmTC_ddb8d/fast' failed
make[1]: *** [cmTC_ddb8d/fast] Error 2
make[1]: Leaving directory '/home/peko/autobuild/instance-0/output/build/libcpprestsdk-v2.10.8/Release/CMakeFiles/CMakeTmp'