message: Don't use gcc's non-standandard abi::__cxa_demangle with clang's libc++
diff: #include <DbgHelp.h>
  #else
  #include <execinfo.h> // for backtrace()
  + #include <ciso646>
  + #if !defined(_LIBCPP_VERSION)
  #include <cxxabi.h> // for abi::__cxa_demangle
  #endif
  +#endif
  constexpr int MAX_FRAMES = 25;
  @@ -122,9 +125,13 @@ std::string demangle( char* backtraceString, int frame )
  *returnOffset = 0;
  ++returnOffset;
  - int status;
  + int status = false;
  +#if !defined(_LIBCPP_VERSION)
  char* realName = abi::__cxa_demangle( mangledName, nullptr, nullptr,
  &status );
  +#else
  + char* realName = mangledName;
  +#endif
  // if demangling is successful, output the demangled function name
  if (status == 0)
  