SF: dispatch add testing surface for VSyncDispatch

Adds a stubbable/mockable surface to the VSyncDispatch class so that
an test relying on this object can be built.

Bug: 140303479
Test: libsurfaceflinger_unittest --gtest_filter="VSyncDisp*"

Change-Id: I7e0a6b14e7032c89c32595a624eef4f75e1ea1ad
diff --git a/services/surfaceflinger/Android.bp b/services/surfaceflinger/Android.bp
index 4226e9a..f529a44 100644
--- a/services/surfaceflinger/Android.bp
+++ b/services/surfaceflinger/Android.bp
@@ -165,7 +165,7 @@
         "Scheduler/PhaseOffsets.cpp",
         "Scheduler/Scheduler.cpp",
         "Scheduler/SchedulerUtils.cpp",
-        "Scheduler/VSyncDispatch.cpp",
+        "Scheduler/VSyncDispatchTimerQueue.cpp",
         "Scheduler/VSyncModulator.cpp",
         "StartPropertySetThread.cpp",
         "SurfaceFlinger.cpp",