CE: Default-Initialize shadowRadius and a timestamp

The unit tests in particular assume that all values are initialzed to
some reasonable default.

The OutputTest takesEarlyOutIfLayerHasEmptyVisibleRegion was aborting on
an integer overflow inside Rect::inset() because an uninitialized
shadowRadius was being converted to -INT32_MIN.

The OutputTest gathersClientCompositionRequests() was sometimes failing because it
assumes that the timestamp is set to zero by default, and is set to a
(nonzero) value by the code under test.

With both these fixes, the CompositionEngine tests pass.

Test: atest libcompositionengine_test
Bug: None
Change-Id: I7ff56a0f24f6d5960493b18458f52766f955151d
diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/LayerFECompositionState.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/LayerFECompositionState.h
index 8a9763b..b4ed92f 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/LayerFECompositionState.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/LayerFECompositionState.h
@@ -116,7 +116,7 @@
     FloatRect geomLayerBounds;
 
     // length of the shadow in screen space
-    float shadowRadius;
+    float shadowRadius{0.f};
 
     /*
      * Geometry state