Assume that this code wants to append a number, not a character

The original code in 2638faa2e8
"writerfilter08ooo330: applied patch for writerfilter08" used OUString::valueOf,
which 64b993e046 "finish deprecation of
O(U)String::valueOf()" changed to a OUString ctor instead of OUString::number
(as that change did for almost all other cases), but without giving a rationale
for this particular case.  But as nUnique starts out as zero, so in the first
round would append a NUL character to "DOCX-Standard", it looks plausible that
this code should add a number after all.

Change-Id: I47136486e28b946fa334a416d1d2fe20ad616ff0

writerfilter/source/dmapper/FormControlHelper.cxx

@@ -98,7 +98,7 @@ uno::Reference<form::XForm> FormControlHelper::FormControlHelper_Impl::getForm()
             {
                 ++nUnique;
                 sFormName = sDOCXForm;
-                sFormName += OUString(nUnique);
+                sFormName += OUString::number(nUnique);
             }
 
             uno::Reference<uno::XInterface> xForm(getServiceFactory()->createInstance("com.sun.star.form.component.Form"));