Drop unused 'using namespace' here

Change-Id: Iffd9e68cbefae664374ca8ad75441f899b849f34
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/123168
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
diff --git a/xmloff/source/core/xmlexp.cxx b/xmloff/source/core/xmlexp.cxx
index 0fd65e1..5e0e46d 100644
--- a/xmloff/source/core/xmlexp.cxx
+++ b/xmloff/source/core/xmlexp.cxx
@@ -98,7 +98,6 @@
#include <comphelper/xmltools.hxx>
#include <comphelper/graphicmimetype.hxx>

using namespace ::osl;
using namespace ::com::sun::star;
using namespace ::com::sun::star::uno;
using namespace ::com::sun::star::frame;