take the state transform into account with h/w composer hal

if the state transform didn't preserve rectangles, we
would still try to use h/w composer hal using the bounds
of the transformed rect, which isn't correct.

now we correctly fall back to composition.

Change-Id: Iff78f4339ece415d4987e95a5717b04934d370ab
diff --git a/services/surfaceflinger/Transform.cpp b/services/surfaceflinger/Transform.cpp
index 0467a14..4cedcbf 100644
--- a/services/surfaceflinger/Transform.cpp
+++ b/services/surfaceflinger/Transform.cpp
@@ -308,6 +308,7 @@
                 scale = true;
             }
         } else {
+            // there is a skew component and/or a non 90 degrees rotation
             flags = ROT_INVALID;
         }