INT 21 - European MS-DOS 4.0 - SEND SIGNAL                                      
	AH = 8Dh
	AL = signal number (see #01793)
	BH = signal argument
	BL = action
	    00h send to entire command subtree
	    01h send only to specified process
	DX = Process ID
Return: CF clear if successful
	CF set on error
	    AX = error code (01h,06h)(see #01680 at AH=59h/BX=0000h)
Desc:	invoke the exceptional-condition handler for the specified process
Note:	error 06h may be returned if one or more of the affected processes
	  have an error handler for the signal
SeeAlso: AH=8Ch