[syslinux] help text key F10 in pxelinux > 3.61

[Alexander Feller]

Hi,

i have a strange problem since pxelinux 3.62 with the F10 help key.
I configured this:
DISPLAY pxelinux.cfg/schlunix_new.txt
F1 pxelinux.cfg/helps/schlunix
F2 pxelinux.cfg/helps/schlunix64
F3 pxelinux.cfg/helps/rescue
F4 pxelinux.cfg/helps/rescue64
F5 pxelinux.cfg/helps/stress
F6 pxelinux.cfg/helps/stress64
F7 pxelinux.cfg/helps/dosimages
F8 pxelinux.cfg/helps/mailsystem
F9 pxelinux.cfg/helps/mailsystem64
F10 pxelinux.cfg/schlunix_new.txt
F11 pxelinux.cfg/helps/ox64
F12 pxelinux.cfg/schlunix_new.txt

If i press F10, the pxelinux try to get "/pxelinux.cfg/schlunix_new.t". 
In this example F10 and F12 do the same. F12 is working fine, but not F10.

In pxelinux < 3.62 works the F10 key correctly (with the same config).

Alex