Determining if the pthread_setname_np exist failed with the following output:
Change Dir: /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/gmake cmTC_00339/fast && gmake[1]: Entering directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
/usr/bin/gmake -f CMakeFiles/cmTC_00339.dir/build.make CMakeFiles/cmTC_00339.dir/build
gmake[2]: Entering directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_00339.dir/CheckSymbolExists.c.o
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/host/bin/arm-linux-gcc --sysroot=/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/host/arm-buildroot-linux-uclibcgnueabi/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  -Os   -DNDEBUG -fPIE   -o CMakeFiles/cmTC_00339.dir/CheckSymbolExists.c.o   -c /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c: In function 'main':
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/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];
                   ^
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/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
gmake[2]: *** [CMakeFiles/cmTC_00339.dir/CheckSymbolExists.c.o] Error 1
gmake[2]: Leaving directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'
gmake[1]: *** [cmTC_00339/fast] Error 2
gmake[1]: Leaving directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/output/build/grpc-1.23.0/CMakeFiles/CMakeTmp'


File /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-1/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
}