writer: Canonicalize no-verity errno to -ENOVERITY

This is what we do elsewhere.

Signed-off-by: Colin Walters <[email protected]>

libcomposefs/lcfs-writer.c

@@ -576,6 +576,8 @@ int lcfs_fd_require_fsverity(uint8_t *digest, int fd)
 	fsv->digest_size = MAX_DIGEST_SIZE;
 	int res = ioctl(fd, FS_IOC_MEASURE_VERITY, fsv);
 	if (res == -1) {
+		if (errno == ENODATA || errno == EOPNOTSUPP || errno == ENOTTY)
+			return -ENOVERITY;
 		return -errno;
 	}
 	// The file has fsverity enabled, but with an unexpected different algorithm (e.g. sha512).