Performing C++ SOURCE FILE Test CMAKE_HAVE_LIBC_PTHREAD failed with the following output:
Change Dir: /home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/gmake -f Makefile cmTC_fa21c/fast && gmake[1]: Entering directory '/home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CMakeTmp'
/usr/bin/gmake  -f CMakeFiles/cmTC_fa21c.dir/build.make CMakeFiles/cmTC_fa21c.dir/build
gmake[2]: Entering directory '/home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_fa21c.dir/src.cxx.o
/home/buildroot/autobuild/instance-2/output-1/host/bin/mips-img-linux-gnu-g++ --sysroot=/home/buildroot/autobuild/instance-2/output-1/host/mips64-buildroot-linux-gnu/sysroot -DCMAKE_HAVE_LIBC_PTHREAD  -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Ofast -g0 -D_FORTIFY_SOURCE=1   -DNDEBUG -o CMakeFiles/cmTC_fa21c.dir/src.cxx.o -c /home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CMakeTmp/src.cxx
Linking CXX executable cmTC_fa21c
/home/buildroot/autobuild/instance-2/output-1/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_fa21c.dir/link.txt --verbose=1
/home/buildroot/autobuild/instance-2/output-1/host/bin/mips-img-linux-gnu-g++ --sysroot=/home/buildroot/autobuild/instance-2/output-1/host/mips64-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Ofast -g0 -D_FORTIFY_SOURCE=1   -DNDEBUG CMakeFiles/cmTC_fa21c.dir/src.cxx.o -o cmTC_fa21c 
CMakeFiles/cmTC_fa21c.dir/src.cxx.o: In function `main':
src.cxx:(.text.startup+0x1c): undefined reference to `pthread_create'
src.cxx:(.text.startup+0x24): undefined reference to `pthread_detach'
src.cxx:(.text.startup+0x2c): undefined reference to `pthread_cancel'
src.cxx:(.text.startup+0x38): undefined reference to `pthread_join'
src.cxx:(.text.startup+0x48): undefined reference to `pthread_atfork'
collect2: error: ld returned 1 exit status
gmake[2]: *** [CMakeFiles/cmTC_fa21c.dir/build.make:99: cmTC_fa21c] Error 1
gmake[2]: Leaving directory '/home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CMakeTmp'
gmake[1]: *** [Makefile:127: cmTC_fa21c/fast] Error 2
gmake[1]: Leaving directory '/home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CMakeTmp'


Source file was:
#include <pthread.h>

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

int main(void)
{
  pthread_t thread;
  pthread_create(&thread, NULL, test_func, NULL);
  pthread_detach(thread);
  pthread_cancel(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: /home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/gmake -f Makefile cmTC_50f22/fast && gmake[1]: Entering directory '/home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CMakeTmp'
/usr/bin/gmake  -f CMakeFiles/cmTC_50f22.dir/build.make CMakeFiles/cmTC_50f22.dir/build
gmake[2]: Entering directory '/home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_50f22.dir/CheckFunctionExists.cxx.o
/home/buildroot/autobuild/instance-2/output-1/host/bin/mips-img-linux-gnu-g++ --sysroot=/home/buildroot/autobuild/instance-2/output-1/host/mips64-buildroot-linux-gnu/sysroot   -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Ofast -g0 -D_FORTIFY_SOURCE=1 -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG -o CMakeFiles/cmTC_50f22.dir/CheckFunctionExists.cxx.o -c /home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CheckLibraryExists/CheckFunctionExists.cxx
Linking CXX executable cmTC_50f22
/home/buildroot/autobuild/instance-2/output-1/host/bin/cmake -E cmake_link_script CMakeFiles/cmTC_50f22.dir/link.txt --verbose=1
/home/buildroot/autobuild/instance-2/output-1/host/bin/mips-img-linux-gnu-g++ --sysroot=/home/buildroot/autobuild/instance-2/output-1/host/mips64-buildroot-linux-gnu/sysroot -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Ofast -g0 -D_FORTIFY_SOURCE=1 -DCHECK_FUNCTION_EXISTS=pthread_create  -DNDEBUG CMakeFiles/cmTC_50f22.dir/CheckFunctionExists.cxx.o -o cmTC_50f22  -lpthreads 
/home/buildroot/autobuild/instance-2/output-1/host/opt/ext-toolchain/bin/../lib/gcc/mips-img-linux-gnu/6.3.0/../../../../mips-img-linux-gnu/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
gmake[2]: *** [CMakeFiles/cmTC_50f22.dir/build.make:99: cmTC_50f22] Error 1
gmake[2]: Leaving directory '/home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CMakeTmp'
gmake[1]: *** [Makefile:127: cmTC_50f22/fast] Error 2
gmake[1]: Leaving directory '/home/buildroot/autobuild/instance-2/output-1/build/libabseil-cpp-20220623.1/CMakeFiles/CMakeTmp'