Incr. MIN_UNDEQUEUED_BUFFERS in SurfaceMediaSource

The buffers in SurfaceMediaSource were 4 earlier, whereas
we need 5 for one of the devices.

Change-Id: I87bf5e28bbb0f7c9661dc01b040baa903d95d2c2
diff --git a/include/media/stagefright/SurfaceMediaSource.h b/include/media/stagefright/SurfaceMediaSource.h
index 74d54d1..97c69cb 100644
--- a/include/media/stagefright/SurfaceMediaSource.h
+++ b/include/media/stagefright/SurfaceMediaSource.h
@@ -34,7 +34,7 @@
 class SurfaceMediaSource : public BnSurfaceTexture, public MediaSource,
                                             public MediaBufferObserver {
 public:
-    enum { MIN_UNDEQUEUED_BUFFERS = 3 };
+    enum { MIN_UNDEQUEUED_BUFFERS = 4 };
     enum {
         MIN_ASYNC_BUFFER_SLOTS = MIN_UNDEQUEUED_BUFFERS + 1,
         MIN_SYNC_BUFFER_SLOTS  = MIN_UNDEQUEUED_BUFFERS