make "rest" param in endsWithIgnoreAsciiCase default to zero

so it matches all of the other endsWith* methods

Change-Id: If6a37056b1225675848434bfb3520e6c496f22e5
(cherry picked from commit e80b9f344aeb88bdbb42d846c0a094d86ee327dc)
Reviewed-on: https://gerrit.libreoffice.org/8655
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>