INT 21 - DOS 2+ - "RMDIR" - REMOVE SUBDIRECTORY
        AH = 3Ah
        DS:DX -> ASCIZ pathname of directory to be removed
Return: CF clear if successful
            AX destroyed
        CF set on error
            AX = error code (03h,05h,06h,10h) (see AH=59h)
Notes:  directory must be empty (contain only '.' and '..' entries)
        under the FlashTek X-32 DOS extender, the pointer is in DS:EDX
SeeAlso: AH=3Bh,AH=E2h/SF=0Bh,INT 2F/AX=1101h