Add temporary layer alpha fallback to OpReorderer

Also adds logic to clip temporary layers to viewport both for
efficiency and to allow large ones (such as the fallback case) to fit
in max texture size.

Change-Id: Iee51495220f5ca1dc7e6f5fd3615db2e896efd74
diff --git a/libs/hwui/Rect.h b/libs/hwui/Rect.h
index 50199db..0736a10 100644
--- a/libs/hwui/Rect.h
+++ b/libs/hwui/Rect.h
@@ -276,7 +276,7 @@
     }
 
     void dump(const char* label = nullptr) const {
-        ALOGD("%s[l=%f t=%f r=%f b=%f]", label ? label : "Rect", left, top, right, bottom);
+        ALOGD("%s[l=%.2f t=%.2f r=%.2f b=%.2f]", label ? label : "Rect", left, top, right, bottom);
     }
 }; // class Rect