btrfs: tests: Fix a memory leak in error handling path in 'run_test()'

If 'btrfs_alloc_path()' fails, we must free the resources already
allocated, as done in the other error handling paths in this function.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Qu Wenruo <quwenruo.btrfs@gmx.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tests/free-space-tree-tests.c

@@ -500,7 +500,8 @@ static int run_test(test_func_t test_func, int bitmaps, u32 sectorsize,
 	path = btrfs_alloc_path();
 	if (!path) {
 		test_msg("Couldn't allocate path\n");
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto out;
 	}
 
 	ret = add_block_group_free_space(&trans, root->fs_info, cache);