Fix bug where checking-in more than once would cause an infinite loop in UsageStatsService

- Forgot to increment loop variable :S

Bug:18239732
Change-Id: Ie37a83584d7849108dbfd3bd4cbb595520d488b1

services/usage/java/com/android/server/usage/UsageStatsDatabase.java

@@ -119,6 +119,7 @@ class UsageStatsDatabase {
                 if (!files.valueAt(start).getBaseFile().getName().endsWith("-c")) {
                     break;
                 }
+                start++;
             }
 
             if (start == fileCount - 1) {