File reproducible.patch of Package xsnow

https://sourceforge.net/p/xsnow/tickets/10/
https://github.com/gitmirrors2/xsnow/commits/openSUSE

commit f955b511e3a707cb3251fd5e7053b997ce7526b1
Author: Bernhard M. Wiedemann <bwiedemann@suse.de>
Date:   Wed Feb 2 07:47:20 2022 +0100

    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.
    This date call is designed to work with various date implementations.
    
    Also use UTC to be independent of timezone.

diff --git a/xsnow/configure b/xsnow/configure
index c969108..1f507b9 100755
--- a/configure
+++ b/configure
@@ -3551,7 +3551,9 @@ fi
 
 
 
-DATE=`date +"%Y-%m-%d"`
+DATE_FMT="+%Y-%m-%d"
+SOURCE_DATE_EPOCH="${SOURCE_DATE_EPOCH:-`date +%s`}"
+DATE=`date -u -d "@$SOURCE_DATE_EPOCH" "$DATE_FMT" 2>/dev/null || date -u -r "$SOURCE_DATE_EPOCH" "$DATE_FMT" 2>/dev/null || date -u "$DATE_FMT"`
 
 
 # Checks for programs.
diff --git a/xsnow/configure.ac b/xsnow/configure.ac
index d08be38..b2d6c23 100644
--- a/configure.ac
+++ b/configure.ac
@@ -35,7 +35,9 @@ AC_ARG_ENABLE(selfrep, [AS_HELP_STRING([--enable-selfrep],[Build with self repli
 AM_CONDITIONAL([MAKESELFREP],[test "x$enable_selfrep" = "xyes"])
 
 AC_SUBST([PACKAGE_VERSION])
-DATE=`date +"%Y-%m-%d"`
+DATE_FMT="+%Y-%m-%d"
+SOURCE_DATE_EPOCH="${SOURCE_DATE_EPOCH:-`date +%s`}"
+DATE=`date -u -d "@$SOURCE_DATE_EPOCH" "$DATE_FMT" 2>/dev/null || date -u -r "$SOURCE_DATE_EPOCH" "$DATE_FMT" 2>/dev/null || date -u "$DATE_FMT"`
 AC_SUBST([DATE])
 
 # Checks for programs.