libgui: Move BitTube out of system include dir

Moves the BitTube header out of the system include directory and into
libgui's include directory.

Test: m -j
Change-Id: I046e3f07ec4a58736c8de7ea7ba0f43a8e3e328b
diff --git a/libs/gui/Android.bp b/libs/gui/Android.bp
index 28c2a48..90ab286 100644
--- a/libs/gui/Android.bp
+++ b/libs/gui/Android.bp
@@ -126,6 +126,10 @@
         "android.hidl.token@1.0-utils",
         "android.hardware.graphics.bufferqueue@1.0",
     ],
+
+    export_include_dirs: [
+        "include",
+    ],
 }
 
 subdirs = ["tests"]
diff --git a/include/private/gui/BitTube.h b/libs/gui/include/private/gui/BitTube.h
similarity index 100%
rename from include/private/gui/BitTube.h
rename to libs/gui/include/private/gui/BitTube.h