Free LDT Descriptor

Frees an LDT descriptor.

Call With:

   AX     = 0001H
   BX     = selector for the descriptor to free

Returns:

   if function successful
   Carry flag= clear

   if function unsuccessful
   Carry flag= set
   AX     = error code
           8022Hinvalid selector

Notes:

o  Each descriptor allocated with Int 31H Fn 0000H
   must be freed individually with this function, even if it
   was previously allocated as part of a contiguous array of
   descriptors.
o  Under DPMI 1.0 hosts, any segment registers which contain
   the selector being freed are zeroed by this function.
o  Refer to the rules for descriptor usage in Appendix D.