QtCore/QCalendarRegistry: Move helper CaseInsensitiveAnyStringViewLessThan out of anonymous namespace

It causes a warning in CMake Unity (Jumbo) builds:

src/corelib/time/qcalendar.cpp:46: warning:
QtPrivate::QCalendarRegistry has a field QtPrivate::QCalendarRegistry::byName whose type uses the anonymous namespace [-Wsubobject-linkage]

Pick-to: 6.5
Task-number: QTBUG-109394
Change-Id: Ie9598c3e87dd835b06cafe5392766bddc258b5ec
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/time/qcalendar.cpp

@@ -25,9 +25,8 @@
 
 QT_BEGIN_NAMESPACE
 
-namespace {
+struct QCalendarRegistryCaseInsensitiveAnyStringViewLessThan
-
+{
-struct CaseInsensitiveAnyStringViewLessThan {
     struct is_transparent {};
     bool operator()(QAnyStringView lhs, QAnyStringView rhs) const
     {
@@ -35,8 +34,6 @@ struct CaseInsensitiveAnyStringViewLessThan {
     }
 };
 
-} // unnamed namespace
-
 namespace QtPrivate {
 
 /*
@@ -70,7 +67,7 @@ class QCalendarRegistry
     */
     QFlatMap<
         QString, QCalendarBackend *,
-        CaseInsensitiveAnyStringViewLessThan,
+        QCalendarRegistryCaseInsensitiveAnyStringViewLessThan,
         QStringList,
         std::vector<QCalendarBackend *>
     > byName;