UserConfig instances contain up to 16 std::shared_ptr<Coprocessor>
instances. We can std::move here to avoid performing 16 redundant atomic
reference increment and decrement operations.
Mostly inconsequential on x64, but we may as well signify intent.
Provides a more "correct" move constructor/assignment operator, since
these relevant functions shouldn't throw exceptions.
Has the benefit of playing nicely with std::move_if_noexcept and other
noexcept library facilities.
