Make sure, that vtysh_cmd.c is deterministically generated.

--- a/vtysh/extract.pl.in	2017-03-10 13:55:06.000000000 +0100
+++ b/vtysh/extract.pl.in	2017-06-24 00:51:56.460000000 +0200
@@ -214,7 +214,7 @@
 }
 
 # Output DEFSH
-foreach (keys %live) {
+foreach (sort keys %live) {
     my ($proto);
     my ($key);
     $key = $live{$_};
@@ -229,7 +229,7 @@
 {
 EOF
 
-foreach (keys %odefun) {
+foreach (sort keys %odefun) {
     my ($node, $str) = (split (/,/));
     $cmd = $ocmd{$_};
     $cmd =~ s/_cmd/_cmd_vtysh/;
href='/guix/'>guix</a></td><td class='form'><form method='get'>
<input type='hidden' name='id' value='397ea21db2c6bb9d5cc589cdc834b07fffe503fc'/><select name='h' onchange='this.form.submit();'>
<option value='koszko' selected='selected'>koszko</option>
<option value='koszko-scripts'>koszko-scripts</option>
</select> <input type='submit' value='switch'/></form></td></tr>
<tr><td class='sub'>Wojtek's customized Guix</td><td class='sub right'></td></tr></table>
<table class='tabs'><tr><td>
<a href='/guix/about/'>about</a><a href='/guix/'>summary</a><a href='/guix/refs/?id=397ea21db2c6bb9d5cc589cdc834b07fffe503fc'>refs</a><a class='active' href='/guix/log/tests/offload.scm'>log</a><a href='/guix/tree/tests/offload.scm?id=397ea21db2c6bb9d5cc589cdc834b07fffe503fc'>tree</a><a href='/guix/commit/tests/offload.scm?id=397ea21db2c6bb9d5cc589cdc834b07fffe503fc'>commit</a><a href='/guix/diff/tests/offload.scm?id=397ea21db2c6bb9d5cc589cdc834b07fffe503fc'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/tests/offload.scm'>
<input type='hidden' name='id' value='397ea21db2c6bb9d5cc589cdc834b07fffe503fc'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=397ea21db2c6bb9d5cc589cdc834b07fffe503fc'>root</a>/<a href='/guix/log/tests?id=397ea21db2c6bb9d5cc589cdc834b07fffe503fc'>tests</a>/<a href='/guix/log/tests/offload.scm?id=397ea21db2c6bb9d5cc589cdc834b07fffe503fc'>offload.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/offload.scm?id=397ea21db2c6bb9d5cc589cdc834b07fffe503fc&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-08-25 13:45:27 -0400'>2020-08-25</span></td><td><a href='/guix/commit/tests/offload.scm?id=4b5a6fbc9b754c0ca70d033dd99f17c4f028733a'>offload: Modify the build-machine record to accept multiple systems.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/scripts/offload.scm (&lt;build-machine&gt;)[systems]: New field.
[system]: Accessor changed to %build-machine-system.  Default to #f.
* guix/scripts/offload.scm (build-machine-system): Wrap %build-machine-system
with a deprecation warning.
(build-machine-systems): Access the new systems field or fallback to use
build-machine-system, for backward compatibility.
(machine-matches?): Adjust.
* tests/offload.scm: Add tests...
* Makefile.am (SCM_TESTS): ...and register them.
* doc/guix.texi (Daemon Offload Setup): Update doc.
</span></span></td><td>Maxim Cournoyer</td></tr>