INT 31 - DPMI 0.9+ - ALLOCATE SPECIFIC LDT DESCRIPTOR

	AX = 000Dh
	BX = LDT selector
Return: CF clear if successful
	    descriptor allocated
	CF set on error
	    AX = error code (DPMI 1.0+) (8011h,8022h) (see #03143)
Notes:	free descriptor with INT 31/AX=0001h
	the first 16 descriptors (04h-7Ch) are reserved for this function, but
	  some may already be in use by other applications under DPMI 0.9;
	  DPMI 1.0 guarantees 16 descriptors per client
	not supported by MS Windows 3.0 in Standard mode
SeeAlso: AX=0000h,AX=0001h