Fix use after free

This could cause an immediate crash or incorrect values might be read
subsequently resulting in incorrect computations.

In QtFlagPropertyManager::uninitializeProperty(QtProperty *): A
pointer to freed memory is dereferenced, used as a function argument, or
otherwise used (CWE-416)

Coverity-Id: 22622
Change-Id: I24fc9d6f7c1c516ddcadaaba2ba7cdaed7c7f807
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

qtpropertybrowser/src/qtpropertymanager.cpp

@@ -5355,8 +5355,8 @@ void QtFlagPropertyManager::setFlagNames(QtProperty *property, const QStringList
     while (itProp.hasNext()) {
         QtProperty *prop = itProp.next();
         if (prop) {
-            delete prop;
             d_ptr->m_flagToProperty.remove(prop);
+            delete prop;
         }
     }
     d_ptr->m_propertyToFlags[property].clear();
@@ -5396,8 +5396,8 @@ void QtFlagPropertyManager::uninitializeProperty(QtProperty *property)
     while (itProp.hasNext()) {
         QtProperty *prop = itProp.next();
         if (prop) {
-            delete prop;
             d_ptr->m_flagToProperty.remove(prop);
+            delete prop;
         }
     }
     d_ptr->m_propertyToFlags.remove(property);