Clipping performance improvements

Create a ClipArea class to handle tracking clip regions. This class can
select the most efficient implementation depending on the types of
clipping presented.

ClipArea re-used the rectangle and region-based clipping
implementations as well as adding a "list of rotated rectangles"
approach that is more efficient for rotated views with children.

Change-Id: I2133761a2462ebc0852b394220e265974b3086f0
diff --git a/libs/hwui/utils/Pair.h b/libs/hwui/utils/Pair.h
index 172606a..0db3aa3 100644
--- a/libs/hwui/utils/Pair.h
+++ b/libs/hwui/utils/Pair.h
@@ -17,6 +17,8 @@
 #ifndef ANDROID_HWUI_PAIR_H
 #define ANDROID_HWUI_PAIR_H
 
+#include <utils/TypeHelpers.h>
+
 namespace android {
 namespace uirenderer {