This addition is useful when an explicit template instantiation of
operator<< is needed, for example, when logging from an ARM mode
function. Example usage:
template mtl::log::stream_type& mtl::log::stream_type::operator<<
<uint16_t>(uint16_t);
ARM_MODE void foo(int16_t x) {
mtl::log::debug << x; // Without the explicit template
instantiation, an ODR violation would occur.
}