Better C++ exception printing for Catch2

catch2-exception-printer.cpp

#include <cxxabi.h>
#include <typeinfo>

CATCH_TRANSLATE_EXCEPTION(const std::exception& e) {
  std::string s;
  int status;

  const char* name = typeid(e).name();
  char* realname = abi::__cxa_demangle(name, 0, 0, &status);
  if (realname) {
    s.append(realname);
  } else {
    s.append(name);
  }
  s.append(": ");
  s.append(e.what());
  free(realname);
  return s;
}