Automatically generate the ChangeLog file from git logs

ChangeLog

@@ -1,2 +1,3 @@
-
+The ChangeLog is auto-generated when releasing. If you are seeing this, use
+'git log' for a detailed list of changes.
 

Makefile.am

@@ -43,3 +43,16 @@ MAINTAINERCLEANFILES = \
 
 -include $(top_srcdir)/git.mk
 
+dist-hook:
+	@if test -d "$(srcdir)/.git"; \
+	then \
+		echo Creating ChangeLog && \
+		( cd "$(top_srcdir)" && \
+		  echo '# Generated by Makefile. Do not edit.'; echo; \
+		  $(top_srcdir)/missing --run git log --stat ) > ChangeLog.tmp \
+		&& mv -f ChangeLog.tmp $(top_distdir)/ChangeLog \
+		|| ( rm -f ChangeLog.tmp ; \
+		     echo Failed to generate ChangeLog >&2 ); \
+	else \
+		echo A git clone is required to generate a ChangeLog >&2; \
+	fi