Align properly in BufferItem::getFlattenedSize.

Test: SurfaceFlinger still works.

Change-Id: I7b5ef08d33a18f98d485f57e461604ed65b657f1
diff --git a/libs/gui/BufferItem.cpp b/libs/gui/BufferItem.cpp
index ec2a9a6..69b5962 100644
--- a/libs/gui/BufferItem.cpp
+++ b/libs/gui/BufferItem.cpp
@@ -91,11 +91,11 @@
     size_t size = sizeof(uint32_t); // Flags
     if (mGraphicBuffer != 0) {
         size += mGraphicBuffer->getFlattenedSize();
-        FlattenableUtils::align<4>(size);
+        size = FlattenableUtils::align<4>(size);
     }
     if (mFence != 0) {
         size += mFence->getFlattenedSize();
-        FlattenableUtils::align<4>(size);
+        size = FlattenableUtils::align<4>(size);
     }
     size += mSurfaceDamage.getFlattenedSize();
     size = FlattenableUtils::align<8>(size);