Fix arithmetic on void pointers in cstp.c
Fix arithmetic on void pointers in cstp.c

This is a gccism and not portable. And could have been dereferencing an
unaligned pointer too. Thanks to Florian Wobbe for pointing it out.

Signed-off-by: David Woodhouse <b460d66aaf00c296a3db1c1d9eeafc081d5f7d70@intel.com>

neshema/openconnect,liiir1985/openconnect,atyndall/openconnect,chadcatlett/openconnect,sihde/openconnect,sihde/openconnect,mveplus/openconnect-client,nmav/openconnect-mine,liiir1985/openconnect,atyndall/openconnect,atyndall/openconnect,liiir1985/openconnect,chadcatlett/openconnect,mdutton3/OpenConnect,matlockx/openconnect,lins05/openconnect,certik/openconnect,certik/openconnect,mveplus/openconnect-client,matlockx/openconnect,don-johnny/openconnect,matlockx/openconnect,mveplus/openconnect-client,mdutton3/OpenConnect,cernekee/openconnect,nmav/openconnect-mine,nmav/openconnect-mine,neshema/openconnect,certik/openconnect,chadcatlett/openconnect,brandt/openconnect,lins05/openconnect,sihde/openconnect,mtmiller/openconnect,mtmiller/openconnect,neshema/openconnect,mtmiller/openconnect,don-johnny/openconnect,brandt/openconnect,cernekee/openconnect,brandt/openconnect,mtmiller/openconnect,cernekee/openconnect,lins05/openconnect,neshema/openconnect,nmav/openconnect-mine,mveplus/openconnect-client,mdutton3/OpenConnect,don-johnny/openconnect,cernekee/openconnect,don-johnny/openconnect,lins05/openconnect,liiir1985/openconnect,chadcatlett/openconnect,brandt/openconnect,matlockx/openconnect,atyndall/openconnect