cmake HAVE_EXECINFO_BACKTRACE_SYMBOLS examples

google/glog CMakeLists.txt :156 

check_cxx_symbol_exists (backtrace_symbols execinfo.h
  HAVE_EXECINFO_BACKTRACE_SYMBOLS)

google/glog CMakeLists.txt :243 

endif (HAVE_EXECINFO_BACKTRACE AND HAVE_EXECINFO_BACKTRACE_SYMBOLS)