[libgda] Use ChangeLog date instead of build date

[Murray Cumming <murrayc src gnome org>]

commit 886091103515019f03eb074bd1ec50c31c85c1a0
Author: Bernhard M. Wiedemann <bwiedemann suse de>
Date:   Mon Oct 23 21:06:42 2017 +0200

    Use ChangeLog date instead of build date
    
    in order to make builds reproducible.
    See https://reproducible-builds.org/ for why this is good.
    
    And use UTC to be independent of timezones.
    
    Without this patch gda-sql.1 would vary for builds on different days.
    
    Bug #789382

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 9898a32..55b3dd7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -78,7 +78,7 @@ CHECK_FD_CLOEXEC([AC_DEFINE(
                   [Whether FD_CLOEXEC is defined.])
                   ])
 
-GDA_BUILDDATE=`date '+%F'`
+GDA_BUILDDATE=`date -u -r ChangeLog '+%F'`
 AC_SUBST(GDA_BUILDDATE, $GDA_BUILDDATE)
 
 dnl **********************