[libxml++] Auto-generate the ChangeLog from the git log for 'make dist'.

[José Alburquerque <jaalburqu src gnome org>]

commit 58724ac0198a299b763a1b6bf10501b10e91f3c2
Author: José Alburquerque <jaalburquerque gmail com>
Date:   Tue Jul 2 17:41:09 2013 -0400

    Auto-generate the ChangeLog from the git log for 'make dist'.
    
        * Makefile.am: Include the dist-changelog.am file copied in build/
        from mm-common so that the ChangeLog is automatically generated from
        the git commit messages on 'make dist'.

 Makefile.am |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index be64b57..d3623ca 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -253,3 +253,5 @@ post-html: docs/index.html
        rsync $(rsync_args) -r docs/index.html $$USER,libxmlplusplus web sourceforge net:$(web_path_project)
        rsync $(rsync_args) -r examples $$USER,libxmlplusplus web sourceforge net:$(web_path_project)
 
+# Optional: auto-generate the ChangeLog file from the git log on make dist
+include $(top_srcdir)/build/dist-changelog.am