Don't encode the current timestamp.

This affects the output of `perl -V`, specifically the message "Compiled
at [...]".

The 'cf_time' and 'cf_by' values show up in 'config.h' and
in 'Config_heavy.pl'.

Use the output of 'uname -s' instead of 'uname -a' to avoid recording
the kernel version ('uname -o' leads to directory names like
'x86_64-gnulinux' instead of 'x86_64-linux', which might cause breakage
down the road.)

diff --git a/perl.c b/perl.c
index 228a0d8..ed38313 100644
--- a/perl.c
+++ b/perl.c
@@ -1825,6 +1825,7 @@ S_Internals_V(pTHX_ CV *cv)
     PUSHs(Perl_newSVpvn_flags(aTHX_ non_bincompat_options,
 			      sizeof(non_bincompat_options) - 1, SVs_TEMP));
 
+#define PERL_BUILD_DATE "Jan  1 1970 00:00:00"
 #ifndef PERL_BUILD_DATE
 #  ifdef __DATE__
 #    ifdef __TIME__

--- a/Configure	1970-01-01 01:00:00.000000000 +0100
+++ b/Configure	2016-10-01 14:47:20.017319739 +0200
@@ -3276,7 +3276,7 @@ $eunicefix tr
 : Try to determine whether config.sh was made on this system
 case "$config_sh" in
 '')
-myuname=`$uname -a 2>/dev/null`
+myuname=`$uname -s 2>/dev/null`
 $test -z "$myuname" && myuname=`hostname 2>/dev/null`
 # Downcase everything to avoid ambiguity.
 # Remove slashes and single quotes so we can use parts of this in
@@ -3845,10 +3845,10 @@
 . ./posthint.sh
 
 : who configured the system
-cf_time=`LC_ALL=C; LANGUAGE=C; export LC_ALL; export LANGUAGE; $date 2>&1`
+cf_time="1970-01-01"
 case "$cf_by" in
 "")
-	cf_by=`(logname) 2>/dev/null`
+	cf_by="guix"
 	case "$cf_by" in
 	"")
 		cf_by=`(whoami) 2>/dev/null`
d><td class='form'><form class='right' method='get' action='/guix/log/gnu/installer/substitutes.scm'>
<input type='hidden' name='id' value='7b38a968296ce238596b294601820bdf1d2b2530'/><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=7b38a968296ce238596b294601820bdf1d2b2530'>root</a>/<a href='/guix/log/gnu?id=7b38a968296ce238596b294601820bdf1d2b2530'>gnu</a>/<a href='/guix/log/gnu/installer?id=7b38a968296ce238596b294601820bdf1d2b2530'>installer</a>/<a href='/guix/log/gnu/installer/substitutes.scm?id=7b38a968296ce238596b294601820bdf1d2b2530'>substitutes.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/gnu/installer/substitutes.scm?id=7b38a968296ce238596b294601820bdf1d2b2530&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-12-11 21:37:07 +0100'>2020-12-11</span></td><td><a href='/guix/commit/gnu/installer/substitutes.scm?id=8361817bf693742757b096468198626f297bb09e'>install: Discover local substitute servers.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/substitutes.scm: New file.
* gnu/installer/newt/substitutes.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add them.
* po/guix/POTFILES.in: Add gnu/installer/newt/substitutes.scm.
* gnu/installer/proxy.scm (with-silent-shepherd): Move to ...
* gnu/installer/utils.scm: ... here.
* gnu/installer/record.scm (&lt;installer&gt;)[substitutes-page]: New field.
* gnu/installer/newt.scm (substitutes-page): New procedure,
(newt-installer): register it.
* gnu/installer.scm (installer-steps): Add "substitutes-page" step.
* gnu/system/install.scm (%installation-services): Add avahi-service-type and
enable substitute server discover in guix-service-type.
[&lt;name-service-switch&gt;]: Set it to %mdns-host-lookup-nss.
</span></span></td><td>Mathieu Othacehe</td></tr>