TC: int dosexterr( struct DOSERR *errinfo )

		MSC: int dosexterr( struct DOSERROR *errinfo )


	- prototype in dos.h

	- returns extended error information (unique to MSDOS 3.0+)
	- errinfo is pointer to DOSERR/DOSERROR structure (defined in dos.h)
	- if 0 returned, previous DOS call did not result in error
	- see   perror