At several places in the ptr_container tests, we have the following pattern:
void f(const std::auto_ptr<int> &); void g() {
f(std::auto_ptr<int>(new int(5)));
}
This is code is ill-formed in C++98/03, because the compiler is
required to check there there exits a copy constructor that would be
able to make a copy of the auto_ptr before binding it to a reference,
even if that copy won't actually be made. Not all compilers diagnose
this error, but Clang and EDG in strict mode do diagnose the problem.
Fixes #4174.