Revert "Android: Don't hold gameFileCache lock during updateAdditionalMetadata"

This reverts commit fb265b610d.

The optimization in that commit is safe when the executor thread is
writing and the GUI thread is reading, but I had failed to take into
account that it's unsafe when the GUI thread is writing and the executor
thread is reading. (The native UpdateAdditionalMetadata function loops
through m_cached_files, which is unsafe if another thread is adding
elements to m_cached_files simultaneously.)

Losing out on this optimization isn't too bad, because
719930bb39 makes it very unlikely that
both threads will want the lock at the same time.

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/services/GameFileCacheManager.java

@@ -227,25 +227,24 @@ public final class GameFileCacheManager
     {
       String[] gamePaths = GameFileCache.getAllGamePaths();
 
-      boolean changed;
       synchronized (sGameFileCache)
       {
-        changed = sGameFileCache.update(gamePaths);
-      }
-      if (changed)
-      {
-        updateGameFileArray();
-      }
+        boolean changed = sGameFileCache.update(gamePaths);
+        if (changed)
+        {
+          updateGameFileArray();
+        }
 
-      boolean additionalMetadataChanged = sGameFileCache.updateAdditionalMetadata();
-      if (additionalMetadataChanged)
-      {
-        updateGameFileArray();
-      }
+        boolean additionalMetadataChanged = sGameFileCache.updateAdditionalMetadata();
+        if (additionalMetadataChanged)
+        {
+          updateGameFileArray();
+        }
 
-      if (changed || additionalMetadataChanged)
-      {
-        sGameFileCache.save();
+        if (changed || additionalMetadataChanged)
+        {
+          sGameFileCache.save();
+        }
       }
     }