xmlSec is the prefix for symbols from libxmlsec, it's confusing if our own code
uses that as well.

Change-Id: I3b003d2de067ba85e9f092c3c6aeac00dd4b1784
Reviewed-on: https://gerrit.libreoffice.org/53820Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>