dash: Fixing NullManager interface implementation.

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
(cherry picked from commit 0a120d112e18f5cde5d57395dd36d18371365ccc)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/stream_filter/dash/mpd/NullManager.cpp

@@ -53,3 +53,7 @@ Representation*         NullManager::getRepresentation       (Period *, long )
 {
     return NULL;
 }
+const MPD*              NullManager::getMPD() const
+{
+    return NULL;
+}

modules/stream_filter/dash/mpd/NullManager.h

@@ -27,6 +27,7 @@
 
 #include "mpd/IMPDManager.h"
 
+#include "mpd/MPD.h"
 #include "mpd/Period.h"
 #include "mpd/Representation.h"
 #include "mpd/ISegment.h"
@@ -45,7 +46,7 @@ namespace dash
                 Representation*         getBestRepresentation   (Period *period);
                 std::vector<ISegment *> getSegments             (Representation *rep);
                 Representation*         getRepresentation       (Period *period, long bitrate);
-
+                const MPD*              getMPD                  () const;
             private:
                 std::vector<Period *>   periods;
                 std::vector<ISegment *> segments;