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

Run Build Command:"/usr/bin/make" "cmTC_1118a/fast"
make[1]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_1118a.dir/build.make CMakeFiles/cmTC_1118a.dir/build
make[2]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_1118a.dir/CheckSymbolExists.c.o
/data/buildroot/buildroot-test/instance-0/output/host/bin/mips-linux-gnu-gcc --sysroot=/data/buildroot/buildroot-test/instance-0/output/host/mips-buildroot-linux-gnu/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG   -o CMakeFiles/cmTC_1118a.dir/CheckSymbolExists.c.o   -c /data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_1118a
/data/buildroot/buildroot-test/instance-0/output/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_1118a.dir/link.txt --verbose=1
/data/buildroot/buildroot-test/instance-0/output/host/bin/mips-linux-gnu-gcc --sysroot=/data/buildroot/buildroot-test/instance-0/output/host/mips-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG    -rdynamic CMakeFiles/cmTC_1118a.dir/CheckSymbolExists.c.o  -o cmTC_1118a 
CMakeFiles/cmTC_1118a.dir/CheckSymbolExists.c.o: In function `main':
CheckSymbolExists.c:(.text.startup+0x0): undefined reference to `pthread_create'
CheckSymbolExists.c:(.text.startup+0x8): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/cmTC_1118a.dir/build.make:98: cmTC_1118a] Error 1
make[2]: Leaving directory '/data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:126: cmTC_1118a/fast] Error 2
make[1]: Leaving directory '/data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'

File /data/buildroot/buildroot-test/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: /data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_d3e01/fast"
make[1]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_d3e01.dir/build.make CMakeFiles/cmTC_d3e01.dir/build
make[2]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_d3e01.dir/CheckFunctionExists.c.o
/data/buildroot/buildroot-test/instance-0/output/host/bin/mips-linux-gnu-gcc --sysroot=/data/buildroot/buildroot-test/instance-0/output/host/mips-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_d3e01.dir/CheckFunctionExists.c.o   -c /data/buildroot/buildroot-test/instance-0/output/host/share/cmake-3.8/Modules/CheckFunctionExists.c
Linking C executable cmTC_d3e01
/data/buildroot/buildroot-test/instance-0/output/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_d3e01.dir/link.txt --verbose=1
/data/buildroot/buildroot-test/instance-0/output/host/bin/mips-linux-gnu-gcc --sysroot=/data/buildroot/buildroot-test/instance-0/output/host/mips-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_d3e01.dir/CheckFunctionExists.c.o  -o cmTC_d3e01 -lpthreads 
/data/buildroot/buildroot-test/instance-0/output/host/opt/ext-toolchain/bin/../lib/gcc/mips-linux-gnu/5.3.0/../../../../mips-linux-gnu/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/cmTC_d3e01.dir/build.make:98: cmTC_d3e01] Error 1
make[2]: Leaving directory '/data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:126: cmTC_d3e01/fast] Error 2
make[1]: Leaving directory '/data/buildroot/buildroot-test/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: /data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_0f347/fast"
make[1]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_0f347.dir/build.make CMakeFiles/cmTC_0f347.dir/build
make[2]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_0f347.dir/src.cxx.o
/data/buildroot/buildroot-test/instance-0/output/host/bin/mips-linux-gnu-g++ --sysroot=/data/buildroot/buildroot-test/instance-0/output/host/mips-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_0f347.dir/src.cxx.o -c /data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp/src.cxx
In file included from /data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp/src.cxx:2:0:
/data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp/src.cxx: In function 'int main()':
/data/buildroot/buildroot-test/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();
         ^
make[2]: *** [CMakeFiles/cmTC_0f347.dir/build.make:66: CMakeFiles/cmTC_0f347.dir/src.cxx.o] Error 1
make[2]: Leaving directory '/data/buildroot/buildroot-test/instance-0/output/build/libcpprestsdk-v2.10.12/Release/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:126: cmTC_0f347/fast] Error 2
make[1]: Leaving directory '/data/buildroot/buildroot-test/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();
      }