libobs: Do not lock sources mutex unnecessarily

In obs_load_sources(), the master sources mutex was being locked
seemingly unnecessarily. This could cause race conditions if used
incorrectly.

libobs/obs.c

@@ -2254,7 +2254,6 @@ obs_source_t *obs_load_private_source(obs_data_t *source_data)
 
 void obs_load_sources(obs_data_array_t *array, obs_load_source_cb cb, void *private_data)
 {
-	struct obs_core_data *data = &obs->data;
 	DARRAY(obs_source_t *) sources;
 	size_t count;
 	size_t i;
@@ -2264,8 +2263,6 @@ void obs_load_sources(obs_data_array_t *array, obs_load_source_cb cb, void *priv
 	count = obs_data_array_count(array);
 	da_reserve(sources, count);
 
-	pthread_mutex_lock(&data->sources_mutex);
-
 	for (i = 0; i < count; i++) {
 		obs_data_t *source_data = obs_data_array_item(array, i);
 		obs_source_t *source = obs_load_source(source_data);
@@ -2292,8 +2289,6 @@ void obs_load_sources(obs_data_array_t *array, obs_load_source_cb cb, void *priv
 	for (i = 0; i < sources.num; i++)
 		obs_source_release(sources.array[i]);
 
-	pthread_mutex_unlock(&data->sources_mutex);
-
 	da_free(sources);
 }