We can also allow unicorn to be constructed in 32-bit mode or 64-bit
mode to satisfy the need for both interpreter instances.
Allows this code to compile successfully of non x86-64 architectures.
shared_ptr was used in 2d1984c20c due to a
misunderstanding of how the language generates move constructors and
move assignment operators.
If a destructor is user-provided, then the compiler won't generate the
move constructor and move assignment operators by default--they must be
explicitly opted into.
The reason for the compilation errors is due to the fact that the
language will fall back to attempting to use the copy constructor/copy
assignment operators if the respective move constructor or move
assignment operator is unavailable.
Given that we explicitly opt into them now, the the move constructor and
move assignment operators will be generated as expected.
This isn't used within the class, so it can be removed to simplify the
overall interface.
While we're in the same area, we can simplify a unique_ptr reset() call.
