GPIB__CloseInstrumentDir (ul_pbar_gpib)

 *  Synopsis:
 *    #include <ul_pbar_gpib:gpibdir.h>
 *
 *    int GPIB__CloseInstrumentDir( void )
 *
 *  Function intent:
 *    GPIB__CloseInstrumentDir() closes the instrument directory file opened in
 *    a previous call to GPIB__InitInstrumentDir(), and releases any associated
 *    memory resources.
 *  Function parameters:
 *    none
 *  Function return value:
 *    FSHARE_OK		success
 *    FSHARE_xxx	error closing directory file