This function retrieves watchpoints:

 	Function:	IO$_LD_CONTROL

 	P1 = address of watchpt structures
 	P2 = size in bytes of watchpt buffer
 	P6 = Subfunction: LDIO$K_GET_WATCH

 	This function reads the number of watchpoints:

 	Function:	IO$_LD_CONTROL

 	P6 = Subfunction: LDIO$K_GET_WATCH | LDIO$M_INQUIRE

 	IOSB word 0 = status
 	     word 1 = number of bytes written
 	     longword 1 = current number of watchpoints

 	Errors returned:

 	SS$_INSFMEM	Not enough memory to allocate temporary buffer
 	SS$_ACCVIO	Buffer can not be written
 	SS$_DATALOST	No active watchpoints
 	SS$_IVBUFLEN	Output buffer too small
 	SS$_NORMAL	Successful completion