Determining if the pthread_setname_np exist failed with the following output:
Change Dir: /tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_2fc03/fast && make[1]: Entering directory '/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_2fc03.dir/build.make CMakeFiles/cmTC_2fc03.dir/build
make[2]: Entering directory '/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_2fc03.dir/CheckSymbolExists.c.o
/usr/bin/gcc   -O2 -I/tmp/instance-0/output-1/host/include  -fPIE   -o CMakeFiles/cmTC_2fc03.dir/CheckSymbolExists.c.o   -c /tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c
/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c: In function 'main':
/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c:8:19: error: 'pthread_setname_np' undeclared (first use in this function); did you mean 'pthread_setcanceltype'?
    8 |   return ((int*)(&pthread_setname_np))[argc];
      |                   ^~~~~~~~~~~~~~~~~~
      |                   pthread_setcanceltype
/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp/CheckSymbolExists.c:8:19: note: each undeclared identifier is reported only once for each function it appears in
make[2]: *** [CMakeFiles/cmTC_2fc03.dir/build.make:66: CMakeFiles/cmTC_2fc03.dir/CheckSymbolExists.c.o] Error 1
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make[1]: *** [Makefile:121: cmTC_2fc03/fast] Error 2
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File /tmp/instance-0/output-1/build/host-grpc-1.31.0/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
}
Performing C SOURCE FILE Test CMAKE_HAVE_LIBC_PTHREAD failed with the following output:
Change Dir: /tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_20bfb/fast && make[1]: Entering directory '/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_20bfb.dir/build.make CMakeFiles/cmTC_20bfb.dir/build
make[2]: Entering directory '/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_20bfb.dir/src.c.o
/usr/bin/gcc   -O2 -I/tmp/instance-0/output-1/host/include  -DCMAKE_HAVE_LIBC_PTHREAD -fPIE   -o CMakeFiles/cmTC_20bfb.dir/src.c.o   -c /tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp/src.c
Linking C executable cmTC_20bfb
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_20bfb.dir/link.txt --verbose=1
/usr/bin/gcc -O2 -I/tmp/instance-0/output-1/host/include  -DCMAKE_HAVE_LIBC_PTHREAD  -L/tmp/instance-0/output-1/host/lib -Wl,-rpath,/tmp/instance-0/output-1/host/lib  CMakeFiles/cmTC_20bfb.dir/src.c.o  -o cmTC_20bfb 
/usr/bin/ld: CMakeFiles/cmTC_20bfb.dir/src.c.o: in function `main':
src.c:(.text.startup+0x29): undefined reference to `pthread_create'
/usr/bin/ld: src.c:(.text.startup+0x32): undefined reference to `pthread_detach'
/usr/bin/ld: src.c:(.text.startup+0x3d): undefined reference to `pthread_join'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/cmTC_20bfb.dir/build.make:87: cmTC_20bfb] Error 1
make[2]: Leaving directory '/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:121: cmTC_20bfb/fast] Error 2
make[1]: Leaving directory '/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp'


Source file was:
#include <pthread.h>

void* test_func(void* data)
{
  return data;
}

int main(void)
{
  pthread_t thread;
  pthread_create(&thread, NULL, test_func, NULL);
  pthread_detach(thread);
  pthread_join(thread, NULL);
  pthread_atfork(NULL, NULL, NULL);
  pthread_exit(NULL);

  return 0;
}

Determining if the function pthread_create exists in the pthreads failed with the following output:
Change Dir: /tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_415bc/fast && make[1]: Entering directory '/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_415bc.dir/build.make CMakeFiles/cmTC_415bc.dir/build
make[2]: Entering directory '/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_415bc.dir/CheckFunctionExists.c.o
/usr/bin/gcc   -O2 -I/tmp/instance-0/output-1/host/include  -DCHECK_FUNCTION_EXISTS=pthread_create -fPIE   -o CMakeFiles/cmTC_415bc.dir/CheckFunctionExists.c.o   -c /usr/share/cmake-3.16/Modules/CheckFunctionExists.c
Linking C executable cmTC_415bc
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_415bc.dir/link.txt --verbose=1
/usr/bin/gcc -O2 -I/tmp/instance-0/output-1/host/include  -DCHECK_FUNCTION_EXISTS=pthread_create  -L/tmp/instance-0/output-1/host/lib -Wl,-rpath,/tmp/instance-0/output-1/host/lib  CMakeFiles/cmTC_415bc.dir/CheckFunctionExists.c.o  -o cmTC_415bc  -lpthreads 
/usr/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/cmTC_415bc.dir/build.make:87: cmTC_415bc] Error 1
make[2]: Leaving directory '/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp'
make[1]: *** [Makefile:121: cmTC_415bc/fast] Error 2
make[1]: Leaving directory '/tmp/instance-0/output-1/build/host-grpc-1.31.0/CMakeFiles/CMakeTmp'