fix uninitialized attribute in SurfaceFlinger

Change-Id: I8277f67e297a8b6a99195387060d03154a2cd929
diff --git a/services/surfaceflinger/GLExtensions.cpp b/services/surfaceflinger/GLExtensions.cpp
index 493122d..0cbf4b1 100644
--- a/services/surfaceflinger/GLExtensions.cpp
+++ b/services/surfaceflinger/GLExtensions.cpp
@@ -28,7 +28,8 @@
 GLExtensions::GLExtensions()
     : mHaveTextureExternal(false),
       mHaveNpot(false),
-      mHaveDirectTexture(false)
+      mHaveDirectTexture(false),
+      mHaveFramebufferObject(false)
 {
 }