and remove that 'using namespace' statement in the header...

Change-Id: I2f994af5088ce6d1ffe92c8d36285a4f6fdd2248
Reviewed-on: https://gerrit.libreoffice.org/24628Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Kohei Yoshida <libreoffice@kohei.us>