Windows: Fix trailing blank in native file dialog filter

Strip trailing blanks when not filtering by suffix.
Amends 76735f3fa0.

Pick-to: 5.15
Fixes: QTBUG-85423
Task-number: QTBUG-42405
Change-Id: Ic13a4e7718f7f1935b1fc329a7beaf1d357fd44d
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

src/plugins/platforms/windows/qwindowsdialoghelpers.cpp

@@ -1087,8 +1087,11 @@ void QWindowsNativeFileDialogBase::setNameFilters(const QStringList &filters)
         const QString &filter = specs[i].filter;
         if (!m_hideFiltersDetails && !filter.startsWith(u"*.")) {
             const int pos = description.lastIndexOf(u'(');
-            if (pos > 0)
+            if (pos > 0) {
                 description.truncate(pos);
+                while (!description.isEmpty() && description.back().isSpace())
+                    description.chop(1);
+            }
         }
         // Add to buffer.
         comFilterSpec[i].pszName = ptr;