fix build. optional test broke.

Change-Id: I0ed5e2cd4c8945ee95673ed0eec5820d9def5097
diff --git a/cmds/flatland/GLHelper.cpp b/cmds/flatland/GLHelper.cpp
index 3928039..42694b3 100644
--- a/cmds/flatland/GLHelper.cpp
+++ b/cmds/flatland/GLHelper.cpp
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+
 #include <ui/DisplayInfo.h>
 #include <gui/SurfaceComposerClient.h>