[QtSingleApplication] Correctly remove lockfile only on app close.

Fixes regression when multiple instances of browser were opened.

src/lib/3rdparty/qtlocalpeer.cpp

@@ -178,6 +178,10 @@ bool QtLocalPeer::sendMessage(const QString &message, int timeout)
     return res;
 }
 
+void QtLocalPeer::removeLockedFile()
+{
+    lockFile.remove();
+}
 
 void QtLocalPeer::receiveConnection()
 {

src/lib/3rdparty/qtlocalpeer.h

@@ -68,6 +68,7 @@ public:
     bool sendMessage(const QString &message, int timeout);
     QString applicationId() const
     { return id; }
+    void removeLockedFile();
 
 Q_SIGNALS:
     void messageReceived(const QString &message);

src/lib/3rdparty/qtlockedfile_unix.cpp

@@ -123,7 +123,5 @@ QtLockedFile::~QtLockedFile()
     if (isOpen()) {
         unlock();
     }
-
-    remove();
 }
 

src/lib/3rdparty/qtsingleapplication.cpp

@@ -277,6 +277,11 @@ QWidget* QtSingleApplication::activationWindow() const
     return actWin;
 }
 
+void QtSingleApplication::removeLockedFile()
+{
+    peer->removeLockedFile();
+}
+
 
 /*!
   De-minimizes, raises, and activates this application's activation window.

src/lib/3rdparty/qtsingleapplication.h

@@ -84,6 +84,8 @@ public:
     void initialize(bool dummy = true)
     { isRunning(); Q_UNUSED(dummy) }
 
+    void removeLockedFile();
+
 public Q_SLOTS:
     bool sendMessage(const QString &message, int timeout = 5000);
     void activateWindow();

src/lib/app/mainapplication.cpp

@@ -747,6 +747,7 @@ void MainApplication::quitApplication()
     //
     //  * this can occur on Mac OS (see #157)
 
+    removeLockedFile();
     quit();
 }