make sure we have a db in SyncFlags, bullet proofing for crash going offline r/sr=sspitzer 181372

mailnews/imap/src/nsImapMailFolder.cpp

@@ -3961,7 +3961,9 @@ nsImapMailFolder::BeginMessageUpload()
 
 // synchronize the message flags in the database with the server flags
 nsresult nsImapMailFolder::SyncFlags(nsIImapFlagAndUidState *flagState)
-{
+{
+  nsresult rv = GetDatabase(nsnull); // we need a database for this
+  NS_ENSURE_SUCCESS(rv, rv);
     // update all of the database flags
   PRInt32 messageIndex;
   PRUint32 messageSize;