INT 21 - Phar Lap 386/DOS-Extender - GET SEGMENT ATTRIBUTES

	AX = 2515h
	BX = segment selector of descriptor in GDT or LDT
Return: CF clear if successful
	    CL = access-rights byte for segment
	    CH = use-type bit (USE16 or USE32)
	ECX<16-31> destroyed
	CF set on error
	    EAX = error code
		09h invalid segment selector in BX
SeeAlso: AX=2514h