QVarLengthArray: implement ### Qt 7 remarks

The header qvarlengtharray.h isn't listed for the Bootstrap lib, but it
is used by several .cpp files that are in that lib (like qstring.cpp).

Change-Id: I69ecc04064514f939896fffd172f78e0f4e37391
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/corelib/tools/qvarlengtharray.h

@@ -241,8 +241,13 @@ protected:
 // Prealloc = 256 by default, specified in qcontainerfwd.h
 template<class T, qsizetype Prealloc>
 class QVarLengthArray
-    : public QVLABase<T>, // ### Qt 7: swap base class order
+#if QT_VERSION >= QT_VERSION_CHECK(7,0,0) || defined(QT_BOOTSTRAPPED)
+    : public QVLAStorage<sizeof(T), alignof(T), Prealloc>,
+      public QVLABase<T>
+#else
+    : public QVLABase<T>,
       public QVLAStorage<sizeof(T), alignof(T), Prealloc>
+#endif
 {
     template <class S, qsizetype Prealloc2>
     friend class QVarLengthArray;