Import_info.Impltype nonrec t = tThe import info for an implementation we depend on and whose .cmx we actually loaded.
The import info for an implementation we depend on but for which we never loaded a .cmx (and thus have no CRC for).
create cu ~crc is create_loaded if crc is Some and create_unloaded if crc is None. Useful when crc is coming out of Consistbl.
val dummy : t