Fixed used after free bug in ffi_type_array_create

[xtldr]

In middle::types::ffi_type_array_create the ffi_type of element is copied to new, but when element is dropped at the end of the loop, the ffi_type is deallocated while still readable from new.

If we add forget(element), the ffi_type won't be deallocated. Since Type::drop only deallocates it's ffi_type, this should be safe because the ffi_type is now owned by the resulting TypeArray.