QCoreApplication: use the correct typedef of preRList

`QVFuncList` and `QStartUpFuncList` are identical typdefs
(`QtCleanUpFunction` and `QtStartUpFunction` are identical typedefs):
typedef QList<QtCleanUpFunction> QVFuncList;
typedef QList<QtStartUpFunction> QStartUpFuncList;

So from the compiler's POV QVFuncList and QStartUpFuncList can be used
interchangeably, but from a code reader's POV, this is confusing.

Use IILE to make the local variable const.

This amends commits 942922652481347659a0dae78758c334778a58d2 and
a887891271a52b2546265c13c6dc70fdd08507e3.

Pick-to: 6.5 6.2 5.15
Fixes: QTBUG-117242
Change-Id: I67f6af89027fe36a1915e815acd3c9446f7dcd5d
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
(cherry picked from commit 408799de65aaa4adcc6660c444f98bfb1a326dfe)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/kernel/qcoreapplication.cpp

@@ -294,15 +294,15 @@ static void qt_call_pre_routines()
     if (!preRList.exists())
         return;
 
-    QVFuncList list;
-    {
+    const QStartUpFuncList list = [] {
         const auto locker = qt_scoped_lock(globalRoutinesMutex);
         // Unlike qt_call_post_routines, we don't empty the list, because
         // Q_COREAPP_STARTUP_FUNCTION is a macro, so the user expects
         // the function to be executed every time QCoreApplication is created.
-        list = *preRList;
-    }
-    for (QtCleanUpFunction f : std::as_const(list))
+        return *preRList;
+    }();
+
+    for (QtStartUpFunction f : list)
         f();
 }