Add another missing <string.h>
Add another missing <string.h>

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

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