[gnome-dvb-daemon] Fix compilation errors with latest Vala version

[Sebastian Pölsterl <sebp src gnome org>]

commit 149ffb0e661045a97e66e0d3bf9dbce0c7acac3e
Author: Sebastian Pölsterl <sebp k-d-w org>
Date:   Sun Aug 16 12:43:14 2020 +0200

    Fix compilation errors with latest Vala version

 src/ChannelFactory.vala                 | 2 +-
 src/Parameter.vala                      | 2 +-
 src/database/sqlite/SqliteDatabase.vala | 2 +-
 src/rtsp/Server.vala                    | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/src/ChannelFactory.vala b/src/ChannelFactory.vala
index c14bc85..daf7f98 100644
--- a/src/ChannelFactory.vala
+++ b/src/ChannelFactory.vala
@@ -252,7 +252,7 @@ namespace DVB {
             return bin;
         }
 
-        private static int find_element (GLib.Value av, Gst.Element bv) {
+        private static int find_element (GLib.Value? av, Gst.Element bv) {
             Gst.Element a = (Gst.Element)av;
             Gst.Element b = (Gst.Element)bv;
             if (a == b) return 0;
diff --git a/src/Parameter.vala b/src/Parameter.vala
index 8ee807c..3ba50f0 100644
--- a/src/Parameter.vala
+++ b/src/Parameter.vala
@@ -32,7 +32,7 @@ namespace DVB {
         public uint Frequency { get; protected set; }
 
         // Constructor
-        public Parameter (DvbSrcDelsys delsys) {
+        protected Parameter (DvbSrcDelsys delsys) {
             base (Delsys: delsys);
         }
 
diff --git a/src/database/sqlite/SqliteDatabase.vala b/src/database/sqlite/SqliteDatabase.vala
index 766950d..16b8661 100644
--- a/src/database/sqlite/SqliteDatabase.vala
+++ b/src/database/sqlite/SqliteDatabase.vala
@@ -32,7 +32,7 @@ namespace DVB.database.sqlite {
         protected Database db;
         private int new_version;
 
-        public SqliteDatabase (File dbfile, int version) {
+        protected SqliteDatabase (File dbfile, int version) {
             base (database_file: dbfile);
             this.new_version = version;
         }
diff --git a/src/rtsp/Server.vala b/src/rtsp/Server.vala
index 10162f8..670f7c9 100644
--- a/src/rtsp/Server.vala
+++ b/src/rtsp/Server.vala
@@ -31,7 +31,7 @@ namespace DVB.RTSPServer {
         string iface = settings.get_streaming_interface ();
 
         string? address = null;
-        GLib.List<unowned cUtils.NetAdapter?> adapters = cUtils.get_adapters ();
+        GLib.List<cUtils.NetAdapter?> adapters = cUtils.get_adapters ();
         foreach (unowned cUtils.NetAdapter? na in adapters) {
             if (na.name == iface) {
                 address = na.address;