Update: std::as_const will be in C++17, in the <utility> header.
Prior to C++17, there’s no built-in syntax for it; however, you can easily write a convenience wrapper:
template<typename T> constexpr const T &as_const(T &t) noexcept { return t; }
for (auto &v: as_const(container))
Note that this calls begin() const rather than cbegin() specifically; the Standard container general requirements specify that cbegin() and begin() const behave identically.
If your container treats non-const iteration specially, it might make sense for it itself to have a member function:
const Container &crange() const noexcept { return *this; }
for (auto &v: container.crange())