Clear old secondary dex dir when multidex becomes supported.

There may be a need for clearing those unused extracted files after an OTA
bringing Art L on the device.

Bug: 10447095

Change-Id: I80b9c0afa2bd8dfa0cf04e96fb04ba2527da0fe5
diff --git a/library/src/android/support/multidex/MultiDexExtractor.java b/library/src/android/support/multidex/MultiDexExtractor.java
index 99c5269..fd70dee 100644
--- a/library/src/android/support/multidex/MultiDexExtractor.java
+++ b/library/src/android/support/multidex/MultiDexExtractor.java
@@ -273,12 +273,12 @@
             return;
         }
         for (File oldFile : files) {
-            Log.w(TAG, "Trying to delete old file " + oldFile.getPath() + " of size " +
+            Log.i(TAG, "Trying to delete old file " + oldFile.getPath() + " of size " +
                     oldFile.length());
             if (!oldFile.delete()) {
                 Log.w(TAG, "Failed to delete old file " + oldFile.getPath());
             } else {
-                Log.w(TAG, "Deleted old file " + oldFile.getPath());
+                Log.i(TAG, "Deleted old file " + oldFile.getPath());
             }
         }
     }