libcpucycles: add update script (#339585)

pkgs/by-name/li/libcpucycles/package.nix

···
     install_name_tool -change "libcpucycles.1.dylib" "$out/lib/libcpucycles.1.dylib" "$out/bin/cpucycles-info"
   '';
 
+  passthru.updateScript = ./update.sh;
+
   meta = {
     homepage = "https://cpucycles.cr.yp.to/";
     description = "Microlibrary for counting CPU cycles";

pkgs/by-name/li/libcpucycles/update.sh

···
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p curl cacert nix common-updater-scripts --pure
+#shellcheck shell=bash
+
+set -eu -o pipefail
+
+# upstream doesn't use git, but has this file specifically for versioning
+version="$(curl https://cpucycles.cr.yp.to/libcpucycles-latest-version.txt)"
+
+update-source-version libcpucycles "$version"
+