Don't use iterators to temporary containers

Fix a clazy warning, like:
Don't call QVector::begin() on temporary [clazy-temporary-iterator]

Indeed, we may pass begin and end iterators for 2 different
instances of temporary vector (shared though).

In addition: use const iterators.

Change-Id: Iac1055d9fc226f1b48ca72ee4f3aab433addfe7f
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmlpreview/qmldebugtranslationwidget.cpp

@@ -76,13 +76,13 @@
 namespace {
 QObject *getPreviewPlugin()
 {
-    auto pluginIt = std::find_if(ExtensionSystem::PluginManager::plugins().begin(),
-                                 ExtensionSystem::PluginManager::plugins().end(),
+    const QVector<ExtensionSystem::PluginSpec *> &specs = ExtensionSystem::PluginManager::plugins();
+    const auto pluginIt = std::find_if(specs.cbegin(), specs.cend(),
                                  [](const ExtensionSystem::PluginSpec *p) {
         return p->name() == "QmlPreview";
     });
 
-    if (pluginIt != ExtensionSystem::PluginManager::plugins().constEnd())
+    if (pluginIt != specs.cend())
         return (*pluginIt)->plugin();
 
     return nullptr;