Test for NPE in EasSyncService during alarm() call

Bug: 2681197
Change-Id: I1795f81ef5a41440fa6fa17f278562fc076dff3f

src/com/android/exchange/EasSyncService.java

@@ -235,6 +235,7 @@ public class EasSyncService extends AbstractSyncService {
      */
     public boolean alarm() {
         HttpPost post;
+        if (mThread == null) return true;
         String threadName = mThread.getName();
 
         // Synchronize here so that we are guaranteed to have valid mPendingPost and mPostLock