[syslinux] INT 22H AX=000Ah, CL=9 and __syslinux_get_derivative_info()

[Sebastian Herbszt]

comboot.txt says to set CL=9 "to get a valid return in CL for all versions".
The code in __syslinux_get_derivative_info() doesn't set it. Is this comment
obsolete? Looking at comboot.inc suggest this because P_CL is set to SECTOR_SHIFT
for all derivatives but pxelinux which does set P_ECX to MyIP.

- Sebastian