e2fuzz: fix fs handle cleanup when closing fails

Fix the handling of 'fs' when closing the FS fails so that we don't
dereference a NULL pointer.  Adapt to use ext2fs_close_free while
we're at it.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Fixes-Coverity-Bug: 1229241
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/misc/e2fuzz.c b/misc/e2fuzz.c
index 644c9c5..8c989dd 100644
--- a/misc/e2fuzz.c
+++ b/misc/e2fuzz.c
@@ -279,23 +279,20 @@
 	close(fd);
 
 	/* Clean up */
-	ret = ext2fs_close(fs);
+	ret = ext2fs_close_free(&fs);
 	if (ret) {
-		fs = NULL;
 		fprintf(stderr, "%s: error while closing filesystem\n",
 			fsname);
-		goto fail2;
+		return 1;
 	}
 
 	return 0;
 fail3:
 	close(fd);
-fail2:
 	if (corrupt_map != fs->block_map)
 		ext2fs_free_block_bitmap(corrupt_map);
 fail:
-	if (fs)
-		ext2fs_close(fs);
+	ext2fs_close_free(&fs);
 	return 1;
 }