Add all missing deps for building flatpak

With this flatpak is now possible to build and working

pkgs/flatpak/lib/libmpeg2.json

@@ -0,0 +1,24 @@
+{
+    "name": "libmpeg2",
+    "config-opts": [ "--enable-shared", "--disable-static" ],
+    "rm-configure": true,
+    "cleanup": [ "/bin/*mpeg2*" ],
+    "sources": [
+        {
+            "type": "archive",
+            "url": "http://libmpeg2.sourceforge.net/files/libmpeg2-0.5.1.tar.gz",
+            "sha256": "dee22e893cb5fc2b2b6ebd60b88478ab8556cb3b93f9a0d7ce8f3b61851871d4"
+        },
+        {
+            "type": "patch",
+            "path": "libmpeg2-inline.patch"
+        },
+        {
+            "type":"script",
+            "commands":[
+                "autoreconf -fiv"
+            ],
+            "dest-filename":"autogen.sh"
+        }
+    ]
+}