Add missing include to choreographer header.

Change-Id: Id497f3a505211309a08e100b369300e81f84b13b
diff --git a/include/android/choreographer.h b/include/android/choreographer.h
index 0239e2f..02c83dc 100644
--- a/include/android/choreographer.h
+++ b/include/android/choreographer.h
@@ -26,6 +26,8 @@
 #ifndef ANDROID_CHOREOGRAPHER_H
 #define ANDROID_CHOREOGRAPHER_H
 
+#include <sys/cdefs.h>
+
 __BEGIN_DECLS
 
 struct AChoreographer;