clean-up EGL includes

Test: compile and run
Bug: cleanup

Change-Id: Icb6c70c80d455446d7163a20d51c41d9b6e0b578
diff --git a/libs/ui/GraphicBuffer.cpp b/libs/ui/GraphicBuffer.cpp
index 37ebfb3..c4d8f76 100644
--- a/libs/ui/GraphicBuffer.cpp
+++ b/libs/ui/GraphicBuffer.cpp
@@ -17,6 +17,9 @@
 #define LOG_TAG "GraphicBuffer"
 
 #include <ui/GraphicBuffer.h>
+
+#include <cutils/atomic.h>
+
 #include <ui/GrallocMapper.h>
 #include <ui/GraphicBufferAllocator.h>
 #include <ui/GraphicBufferMapper.h>