Determining if the include file execinfo.h exists failed with the following output:
Change Dir: /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/build/libabseil-cpp-20200225/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/gmake cmTC_ca21c/fast && gmake[1]: Entering directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/build/libabseil-cpp-20200225/CMakeFiles/CMakeTmp'
/usr/bin/gmake -f CMakeFiles/cmTC_ca21c.dir/build.make CMakeFiles/cmTC_ca21c.dir/build
gmake[2]: Entering directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/build/libabseil-cpp-20200225/CMakeFiles/CMakeTmp'
Building CXX object CMakeFiles/cmTC_ca21c.dir/CheckIncludeFile.cxx.o
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/host/bin/m68k-linux-g++ --sysroot=/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/host/m68k-buildroot-linux-uclibc/sysroot    -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -O2   -DNDEBUG   -o CMakeFiles/cmTC_ca21c.dir/CheckIncludeFile.cxx.o -c /usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/build/libabseil-cpp-20200225/CMakeFiles/CMakeTmp/CheckIncludeFile.cxx
/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/build/libabseil-cpp-20200225/CMakeFiles/CMakeTmp/CheckIncludeFile.cxx:1:10: fatal error: execinfo.h: No such file or directory
 #include <execinfo.h>
          ^~~~~~~~~~~~
compilation terminated.
gmake[2]: *** [CMakeFiles/cmTC_ca21c.dir/CheckIncludeFile.cxx.o] Error 1
gmake[2]: Leaving directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/build/libabseil-cpp-20200225/CMakeFiles/CMakeTmp'
gmake[1]: *** [cmTC_ca21c/fast] Error 2
gmake[1]: Leaving directory `/usr/lfs/hdd_v1/rc-buildroot-test/scripts/instance-0/output-1/build/libabseil-cpp-20200225/CMakeFiles/CMakeTmp'