Fix breakage from PR #1869 due to using Qt 5 features not supported o…

…n Trusty/Xenial.

Also fixes a potential race condition in MusicBrainzClient/AcoustidClient where
m_requests temporarily contains deleted pointers.

src/control/controlobjectscript.cpp

@@ -57,7 +57,7 @@ void ControlObjectScript::removeScriptConnection(const ScriptConnection& conn) {
 
 void ControlObjectScript::disconnectAllConnectionsToFunction(const QScriptValue& function) {
     // Make a local copy of m_scriptConnections because items are removed within the loop.
-    const QVector<ScriptConnection> connections = m_scriptConnections;
+    const QList<ScriptConnection> connections = m_scriptConnections;
     for (const auto& conn: connections) {
         if (conn.callback.strictlyEquals(function)) {
             removeScriptConnection(conn);
@@ -70,7 +70,7 @@ void ControlObjectScript::slotValueChanged(double value, QObject*) {
     // This allows a script to disconnect a callback from inside the
     // the callback. Otherwise the this may crash since the disconnect call
     // happens during conn.function.call() in the middle of the loop below.
-    const QVector<ScriptConnection> connections = m_scriptConnections;
+    const QList<ScriptConnection> connections = m_scriptConnections;
     for (auto&& conn: connections) {
         conn.executeCallback(value);
     }

src/control/controlobjectscript.h

@@ -38,7 +38,7 @@ class ControlObjectScript : public ControlProxy {
     void slotValueChanged(double v, QObject*);
 
   private:
-    QVector<ScriptConnection> m_scriptConnections;
+    QList<ScriptConnection> m_scriptConnections;
 };
 
 #endif // CONTROLOBJECTSCRIPT_H

src/musicbrainz/acoustidclient.cpp

@@ -66,8 +66,13 @@ void AcoustidClient::cancel(int id) {
 }
 
 void AcoustidClient::cancelAll() {
-    qDeleteAll(m_requests.keyBegin(), m_requests.keyEnd());
+    auto requests = m_requests;
     m_requests.clear();
+
+    for (auto it = requests.constBegin();
+         it != requests.constEnd(); ++it) {
+        delete it.key();
+    }
 }
 
 void AcoustidClient::requestFinished() {

src/musicbrainz/musicbrainzclient.cpp

@@ -59,8 +59,12 @@ void MusicBrainzClient::cancel(int id) {
 }
 
 void MusicBrainzClient::cancelAll() {
-    qDeleteAll(m_requests.keyBegin(), m_requests.keyEnd());
+    auto requests = m_requests;
     m_requests.clear();
+    for (auto it = requests.constBegin();
+         it != requests.constEnd(); ++it) {
+        delete it.key();
+    }
 }
 
 namespace {