Allow vhpiLogicVal and vhpiLogicVecVal as aliases of vhpiEnumVal and vhpiEnumVecVal

According to my reading of the VHPI spec, signals with type std_logic, std_ulogic, or bit, and arrays of those types should use vhpiLogicVal or vhpiLogicVecVal as the native format. This uses the same field in vhpiValueT so allowing this is trivial.