[build] Copy the built ChangeLog to the distdir
[build] Copy the built ChangeLog to the distdir

The ChangeLog built during the dist phase is copied in the
top_srcdir, replacing the stub ChangeLog. Instead, we want
to keep the stub pointing to the commit log, and copy the
generated ChangeLog to top_distdir.

ebassi/twitter-glib,ebassi/twitter-glib