external: Sync with openconnect rev 5550734cb

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
libs/assets: Sync with latest sources

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
AuthFormHandler: Honor the new OC_FORM_OPT_IGNORE flag

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>