Fix paste bug

Bug: 20764843

Pasting in a number changes the expression value.  Duh.

Change-Id: Ia4234632833767fd3d8614f56feec9dcf123ae3c
diff --git a/src/com/android/calculator2/Evaluator.java b/src/com/android/calculator2/Evaluator.java
index e5b1e70..1d164b3 100644
--- a/src/com/android/calculator2/Evaluator.java
+++ b/src/com/android/calculator2/Evaluator.java
@@ -859,6 +859,7 @@
     }
 
     void addSaved() {
+        mChangedValue = true;
         mExpr.append(mSaved);
     }