Doc Update: revert PendingIntent fix.

Original fix was in error. Reverting. See:

b/10641568

Change-Id: I471157388b2d55aa99bd16813c07607b8a0a7046

core/java/android/app/PendingIntent.java

@@ -95,8 +95,8 @@ public final class PendingIntent implements Parcelable {
      */
     public static final int FLAG_ONE_SHOT = 1<<30;
     /**
-     * Flag indicating that if the described PendingIntent already
-     * exists, then simply return null instead of creating it.
+     * Flag indicating that if the described PendingIntent does not
+     * already exist, then simply return null instead of creating it.
      * For use with {@link #getActivity}, {@link #getBroadcast}, and
      * {@link #getService}.
      */