fix circular dependency libnativewindow <-> libui

Bug: 37647680
Bug: 37648355
Test: compile, manual
Change-Id: I9631beea52e23ebb519411f943c6f5062aedd2e5
diff --git a/libs/gui/StreamSplitter.cpp b/libs/gui/StreamSplitter.cpp
index bafe947..52c9067 100644
--- a/libs/gui/StreamSplitter.cpp
+++ b/libs/gui/StreamSplitter.cpp
@@ -31,6 +31,8 @@
 
 #include <utils/Trace.h>
 
+#include <system/window.h>
+
 namespace android {
 
 status_t StreamSplitter::createSplitter(