add reader_queue_speed_test_mode to python init

test=develop

python/paddle/fluid/__init__.py

@@ -113,7 +113,8 @@ def __bootstrap__():
         'use_pinned_memory', 'check_nan_inf', 'benchmark', 'warpctc_dir',
         'eager_delete_scope', 'use_mkldnn', 'initial_cpu_memory_in_mb',
         'init_allocated_mem', 'free_idle_memory', 'paddle_num_threads',
-        "dist_threadpool_size", 'cpu_deterministic', 'eager_delete_tensor_gb'
+        'dist_threadpool_size', 'cpu_deterministic', 'eager_delete_tensor_gb',
+        'reader_queue_speed_test_mode'
     ]
     if core.is_compiled_with_dist():
         read_env_flags.append('rpc_deadline')