Avoid adding duplicate resource classes.

Avoids an issue where multiple Bitmap.class instances were added to the list resulting in duplicate load paths being created.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182292756

library/src/main/java/com/bumptech/glide/provider/ResourceDecoderRegistry.java

@@ -63,7 +63,9 @@ public synchronized <T, R> List<Class<R>> getResourceClasses(@NonNull Class<T> d
       }
       for (Entry<?, ?> entry : entries) {
         if (entry.handles(dataClass, resourceClass)) {
-          result.add((Class<R>) entry.resourceClass);
+          if (!result.contains((Class<R>) entry.resourceClass)) {
+            result.add((Class<R>) entry.resourceClass);
+          }
         }
       }
     }