Log an error when the Crashlytics-specific directory cannot be created, since it means Crashlytics is not working.

Author: mrober

firebase-crashlytics/src/main/java/com/google/firebase/crashlytics/internal/persistence/FileStore.java

@@ -185,7 +185,7 @@ private static synchronized File prepareBaseDir(File file) {
       }
     }
     if (!file.mkdirs()) {
-      Logger.getLogger().d("Could not create Crashlytics-specific directory: " + file);
+      Logger.getLogger().e("Could not create Crashlytics-specific directory: " + file);
     }
     return file;
   }