Auto-generate the ChangeLog file from mercurial logs

Signed-off-by: Jeff Schroeder <jeffschroeder@computer.org>

diff -r 71fd576d8346 Makefile.am
--- a/Makefile.am	Fri Jun 13 12:59:59 2008 -0700
+++ b/Makefile.am	Mon Jun 23 13:42:22 2008 -0700
@@ -15,3 +15,11 @@ pkgconfig_DATA = augeas.pc
 
 distclean-local:
 	-rm -rf $(top_builddir)/build
+
+ChangeLog:
+	@if test -d $(top_srcdir)/.hg; then \
+		hg log --style changelog > $@; \
+	 fi
+dist: ChangeLog
+
+.PHONY: ChangeLog