Return sp on call to createSurfaceInterceptor

This is so that SurfaceInterceptor can implement IBinder::DeathRecipient, since that inherits RefBase.h and must be stored as an sp.

Test: Make sure the device boot when SurfaceInterceptor extends RefBase
Change-Id: I264cd9e0a8517ae5a425b3a493631c7c42220473
diff --git a/services/surfaceflinger/SurfaceInterceptor.cpp b/services/surfaceflinger/SurfaceInterceptor.cpp
index c15d0df..d6b5338 100644
--- a/services/surfaceflinger/SurfaceInterceptor.cpp
+++ b/services/surfaceflinger/SurfaceInterceptor.cpp
@@ -45,6 +45,11 @@
 {
 }
 
+void SurfaceInterceptor::binderDied(const wp<IBinder>& who) {
+    // TODO: Implement
+    (void)who;
+}
+
 void SurfaceInterceptor::enable(const SortedVector<sp<Layer>>& layers,
         const DefaultKeyedVector< wp<IBinder>, DisplayDeviceState>& displays)
 {