Determining if the pthread_setname_np exist failed with the following output:
Change Dir: /data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_0869f/fast"
make[1]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_0869f.dir/build.make CMakeFiles/cmTC_0869f.dir/build
make[2]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_0869f.dir/CheckSymbolExists.c.o
/data/buildroot/buildroot-test/instance-0/output/host/bin/arm-none-linux-gnueabi-gcc --sysroot=/data/buildroot/buildroot-test/instance-0/output/host/arm-buildroot-linux-gnueabi/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG -fPIE   -o CMakeFiles/cmTC_0869f.dir/CheckSymbolExists.c.o   -c /data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c
/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c: In function 'main':
/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c:8:19: error: 'pthread_setname_np' undeclared (first use in this function)
   return ((int*)(&pthread_setname_np))[argc];
                   ^
/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c:8:19: note: each undeclared identifier is reported only once for each function it appears in
make[2]: *** [CMakeFiles/cmTC_0869f.dir/build.make:66: CMakeFiles/cmTC_0869f.dir/CheckSymbolExists.c.o] Error 1
make[2]: Leaving directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:126: cmTC_0869f/fast] Error 2
make[1]: Leaving directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'

File /data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <pthread.h>

int main(int argc, char** argv)
{
  (void)argv;
#ifndef pthread_setname_np
  return ((int*)(&pthread_setname_np))[argc];
#else
  (void)argc;
  return 0;
#endif
}

Determining if the pthread_create exist failed with the following output:
Change Dir: /data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_4a6fd/fast"
make[1]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_4a6fd.dir/build.make CMakeFiles/cmTC_4a6fd.dir/build
make[2]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_4a6fd.dir/CheckSymbolExists.c.o
/data/buildroot/buildroot-test/instance-0/output/host/bin/arm-none-linux-gnueabi-gcc --sysroot=/data/buildroot/buildroot-test/instance-0/output/host/arm-buildroot-linux-gnueabi/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG -fPIE   -o CMakeFiles/cmTC_4a6fd.dir/CheckSymbolExists.c.o   -c /data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_4a6fd
/data/buildroot/buildroot-test/instance-0/output/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_4a6fd.dir/link.txt --verbose=1
/data/buildroot/buildroot-test/instance-0/output/host/bin/arm-none-linux-gnueabi-gcc --sysroot=/data/buildroot/buildroot-test/instance-0/output/host/arm-buildroot-linux-gnueabi/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os   -DNDEBUG  -latomic  CMakeFiles/cmTC_4a6fd.dir/CheckSymbolExists.c.o  -o cmTC_4a6fd 
/data/buildroot/buildroot-test/instance-0/output/host/opt/ext-toolchain/bin/../lib/gcc/arm-none-linux-gnueabi/4.8.3/../../../../arm-none-linux-gnueabi/bin/ld: CMakeFiles/cmTC_4a6fd.dir/CheckSymbolExists.c.o: undefined reference to symbol 'pthread_create@@GLIBC_2.4'
/data/buildroot/buildroot-test/instance-0/output/host/arm-buildroot-linux-gnueabi/sysroot/armv4t/lib/libpthread.so.0: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/cmTC_4a6fd.dir/build.make:98: cmTC_4a6fd] Error 1
make[2]: Leaving directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:126: cmTC_4a6fd/fast] Error 2
make[1]: Leaving directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'

File /data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/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/grpc-1.23.0/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_1645b/fast"
make[1]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_1645b.dir/build.make CMakeFiles/cmTC_1645b.dir/build
make[2]: Entering directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_1645b.dir/CheckFunctionExists.c.o
/data/buildroot/buildroot-test/instance-0/output/host/bin/arm-none-linux-gnueabi-gcc --sysroot=/data/buildroot/buildroot-test/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 -fPIE   -o CMakeFiles/cmTC_1645b.dir/CheckFunctionExists.c.o   -c /data/buildroot/buildroot-test/instance-0/output/host/share/cmake-3.8/Modules/CheckFunctionExists.c
Linking C executable cmTC_1645b
/data/buildroot/buildroot-test/instance-0/output/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_1645b.dir/link.txt --verbose=1
/data/buildroot/buildroot-test/instance-0/output/host/bin/arm-none-linux-gnueabi-gcc --sysroot=/data/buildroot/buildroot-test/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  -latomic  CMakeFiles/cmTC_1645b.dir/CheckFunctionExists.c.o  -o cmTC_1645b -lpthreads 
/data/buildroot/buildroot-test/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
make[2]: *** [CMakeFiles/cmTC_1645b.dir/build.make:98: cmTC_1645b] Error 1
make[2]: Leaving directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:126: cmTC_1645b/fast] Error 2
make[1]: Leaving directory '/data/buildroot/buildroot-test/instance-0/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'