Determining if the pthread_create exist failed with the following output:
Change Dir: /home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_1fe68/fast"
make[1]: Entering directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_1fe68.dir/build.make CMakeFiles/cmTC_1fe68.dir/build
make[2]: Entering directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_1fe68.dir/CheckSymbolExists.c.o
/home/buildroot/autobuild/instance-0/output/host/bin/x86_64-amd-linux-gnu-gcc --sysroot=/home/buildroot/autobuild/instance-0/output/host/x86_64-buildroot-linux-gnu/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG   -o CMakeFiles/cmTC_1fe68.dir/CheckSymbolExists.c.o   -c /home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_1fe68
/home/buildroot/autobuild/instance-0/output/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_1fe68.dir/link.txt --verbose=1
/home/buildroot/autobuild/instance-0/output/host/bin/x86_64-amd-linux-gnu-gcc --sysroot=/home/buildroot/autobuild/instance-0/output/host/x86_64-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG    -rdynamic CMakeFiles/cmTC_1fe68.dir/CheckSymbolExists.c.o  -o cmTC_1fe68 
CMakeFiles/cmTC_1fe68.dir/CheckSymbolExists.c.o: In function `main':
CheckSymbolExists.c:(.text.startup+0x6): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_1fe68.dir/build.make:97: recipe for target 'cmTC_1fe68' failed
make[2]: *** [cmTC_1fe68] Error 1
make[2]: Leaving directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
Makefile:126: recipe for target 'cmTC_1fe68/fast' failed
make[1]: *** [cmTC_1fe68/fast] Error 2
make[1]: Leaving directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'

File /home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/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/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_71c67/fast"
make[1]: Entering directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_71c67.dir/build.make CMakeFiles/cmTC_71c67.dir/build
make[2]: Entering directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_71c67.dir/CheckFunctionExists.c.o
/home/buildroot/autobuild/instance-0/output/host/bin/x86_64-amd-linux-gnu-gcc --sysroot=/home/buildroot/autobuild/instance-0/output/host/x86_64-buildroot-linux-gnu/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG   -o CMakeFiles/cmTC_71c67.dir/CheckFunctionExists.c.o   -c /home/buildroot/autobuild/instance-0/output/host/share/cmake-3.8/Modules/CheckFunctionExists.c
Linking C executable cmTC_71c67
/home/buildroot/autobuild/instance-0/output/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_71c67.dir/link.txt --verbose=1
/home/buildroot/autobuild/instance-0/output/host/bin/x86_64-amd-linux-gnu-gcc --sysroot=/home/buildroot/autobuild/instance-0/output/host/x86_64-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG    -rdynamic CMakeFiles/cmTC_71c67.dir/CheckFunctionExists.c.o  -o cmTC_71c67 -lpthreads 
/home/buildroot/autobuild/instance-0/output/host/opt/ext-toolchain/bin/../lib/gcc/x86_64-amd-linux-gnu/6.2.0/../../../../x86_64-amd-linux-gnu/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_71c67.dir/build.make:97: recipe for target 'cmTC_71c67' failed
make[2]: *** [cmTC_71c67] Error 1
make[2]: Leaving directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
Makefile:126: recipe for target 'cmTC_71c67/fast' failed
make[1]: *** [cmTC_71c67/fast] Error 2
make[1]: Leaving directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'


Performing C++ SOURCE FILE Test _SSL_LEAK_SUPPRESS_AVAILABLE failed with the following output:
Change Dir: /home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_7f03f/fast"
make[1]: Entering directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_7f03f.dir/build.make CMakeFiles/cmTC_7f03f.dir/build
make[2]: Entering directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_7f03f.dir/src.cxx.o
/home/buildroot/autobuild/instance-0/output/host/bin/x86_64-amd-linux-gnu-g++ --sysroot=/home/buildroot/autobuild/instance-0/output/host/x86_64-buildroot-linux-gnu/sysroot    -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  -Os   -latomic -std=c++11 -fno-strict-aliasing -D_SSL_LEAK_SUPPRESS_AVAILABLE  -DNDEBUG   -o CMakeFiles/cmTC_7f03f.dir/src.cxx.o -c /home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp/src.cxx
In file included from /home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp/src.cxx:2:0:
/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp/src.cxx: In function 'int main()':
/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp/src.cxx:5:9: error: expected id-expression before 'while'
       ::SSL_COMP_free_compression_methods();
         ^
CMakeFiles/cmTC_7f03f.dir/build.make:65: recipe for target 'CMakeFiles/cmTC_7f03f.dir/src.cxx.o' failed
make[2]: *** [CMakeFiles/cmTC_7f03f.dir/src.cxx.o] Error 1
make[2]: Leaving directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
Makefile:126: recipe for target 'cmTC_7f03f/fast' failed
make[1]: *** [cmTC_7f03f/fast] Error 2
make[1]: Leaving directory '/home/buildroot/autobuild/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'

Source file was:

      #include <openssl/ssl.h>
      int main()
      {
      ::SSL_COMP_free_compression_methods();
      }