File reproducible.patch of Package gutenprint

https://sourceforge.net/p/gimp-print/source/merge-requests/9/ merged

commit cd85016230120da0db71c98e375b37780242ef56
Author: Bernhard M. Wiedemann <bwiedemann@suse.de>
Date:   Mon Jun 26 08:11:03 2023 +0200

    Allow to override build date with SOURCE_DATE_EPOCH
    
    in order to make builds reproducible.
    See https://reproducible-builds.org/ for why this is good
    and https://reproducible-builds.org/specs/source-date-epoch/
    for the definition of this variable.
    
    Also consistently use ISO 8601 date format to be understood everywhere.
    
    Also use UTC to be independent of timezone.
    
    This patch was done while working on reproducible builds for openSUSE.

diff --git a/configure.ac b/configure.ac
index 6e2d123d..9a749507 100644
--- a/configure
+++ b/configure
@@ -1202,7 +1202,10 @@ echo "$PACKAGE_BUGREPORT" |tee -a config.summary
 echo |tee -a config.summary
 echo "================================================================" |tee -a config.summary
 echo "  Release: $PACKAGE_STRING generated on $RELEASE_DATE" |tee -a config.summary
-echo "  Generated at `date` by $LOGNAME" |tee -a config.summary
+DATE_FMT="+%Y-%m-%dT%H:%M:%S+0000"
+SOURCE_DATE_EPOCH="${SOURCE_DATE_EPOCH:-$(date +%s)}"
+BUILD_DATE=$(date -u -d "@$SOURCE_DATE_EPOCH" "$DATE_FMT" 2>/dev/null || date -u -r "$SOURCE_DATE_EPOCH" "$DATE_FMT" 2>/dev/null || date -u "$DATE_FMT")
+echo "  Generated at $BUILD_DATE by $LOGNAME" |tee -a config.summary
 echo |tee -a config.summary
 echo "  Features:" |tee -a config.summary
 if test "$BUILD_CUPS" != "no" ; then