Turns out NtQueryDirectoryFile only returns a single entry at a time.
- Renamed SHIM_SET_RETURN macro to SHIM_SET_RETURN_64.
- Added SHIM_SET_RETURN_32 macro, which sign-extends to 64-bit.
- Updated all uses of SHIM_SET_RETURN to the appropriate macro (either SHIM_SET_RETURN_32 or SHIM_SET_RETURN_64).