Add @hide tag to fix SDK build

Previous Canvas changes missed a @hide tag, so droiddoc was complaining
about a missing method since that was also hidden.

Change-Id: Ib70a9fa2e20fe32b74ba901bb289e77583164004

core/java/android/text/GraphicsOperations.java

@@ -35,6 +35,7 @@ extends CharSequence
 
     /**
      * Just like {@link Canvas#drawTextRun}.
+     * {@hide}
      */
     void drawTextRun(Canvas c, int start, int end,
                          float x, float y, int flags, Paint p);