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/;
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<tr><td><span title='2019-10-30 18:15:54 -0400'>2019-10-30</span></td><td><a href='/guix/commit/tests/networking.scm?id=97bc3cbea5fc281a299c03eaaa3be5baf21ea673'>services: ntp: Ensure no double quotes are output to config file.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2019-09-08 23:15:32 +0900'>2019-09-08</span></td><td><a href='/guix/commit/tests/networking.scm?id=2625abc6aa5df66a6503e906b7592691452954f5'>services: openntpd: Add test for issue #3731.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2019-09-08 23:15:31 +0900'>2019-09-08</span></td><td><a href='/guix/commit/tests/networking.scm?id=5658ae8a0ad5d988765944b7e783b2bdc23a7f48'>services: ntp: Support different NTP server types and options.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>