DIO__EnableRetry (ul_pbar_dio)

 *  Synopsis:
 *    #include <ul_pbar_dio:dio.h>
 *
 *    int DIO__EnableRetry( const CDIOptr devicePtr, const int retryCount )
 *
 *  Function intent:
 *    DIO__EnableRetry() enables or re-enables DIO I/O error retries for the
 *    DIO device represented by the devicePtr parameter.  If the retryCount
 *    parameter value is zero, the module's retry count will be restored to the
 *    value saved by a previous call to DIO__DisableRetry().  If the retryCount
 *    parameter value is non-zero then the module's retry count will simply
 *    be set to that value.
 *  Function parameters:
 *    CDIOptr	devicePtr	The unique DIO device I/O control pointer
 *                              returned by DIO__InitializeModule().
 *    int	retryCount	# of retry attempts to use on DIO__xxx calls
 *  Function return value:
 *    positive		the previous setting of the device's retry count
 *    CBS_INVARG	devicePtr was NULL or invalid