QFactoryLoader: load extraSearchPath first

Since `QT_QPA_PLATFORM_PLUGIN_PATH` or `-platformpluginpath`
 specifies the path to platform plugins, `extraSearchPath`
 should be loaded first.

Change-Id: I2e62fbf2021250ca864c669a7bbd7d56acd67d1e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 4575809)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit b610831)

src/corelib/plugin/qfactoryloader.cpp

@@ -394,18 +394,18 @@ void QFactoryLoader::update()
 #ifdef QT_SHARED
     Q_D(QFactoryLoader);
 
+    if (!d->extraSearchPath.isEmpty())
+        d->updateSinglePath(d->extraSearchPath);
+
     const QStringList paths = QCoreApplication::libraryPaths();
     for (const QString &pluginDir : paths) {
 #ifdef Q_OS_ANDROID
         QString path = pluginDir;
 #else
         QString path = pluginDir + d->suffix;
 #endif
-
         d->updateSinglePath(path);
     }
-    if (!d->extraSearchPath.isEmpty())
-        d->updateSinglePath(d->extraSearchPath);
 #else
     Q_D(QFactoryLoader);
     qCDebug(lcFactoryLoader) << "ignoring" << d->iid