generate ChangeLog from git logs into distribution tarball

No longer maintain a version-controlled ChangeLog file, but do
continue to include a ChangeLog file in distribution tarball.
* Makefile.am (gen-ChangeLog): New rule.
(dist-hook): Depend on it.
(EXTRA_DIST): Add ChangeLog-old.
* bootstrap (modules): Add gitlog-to-changelog.
* ChangeLog: Remove file.  Renamed to...
* ChangeLog-old: ...this.  New file.
* autogen.sh: Touch ChangeLog, to ensure it exists.  For automake.

Makefile.am

@@ -9,6 +9,7 @@ SUBDIRS = gnulib/lib include src qemud tools proxy docs gnulib/tests \
 ACLOCAL_AMFLAGS = -I m4 -I gnulib/m4
 
 EXTRA_DIST = \
+  ChangeLog-old \
   libvirt.spec libvirt.spec.in \
   mingw32-libvirt.spec.in \
   libvirt.pc libvirt.pc.in \
@@ -49,3 +50,17 @@ clean-cov:
 
 # disable this check
 distuninstallcheck:
+
+dist-hook: gen-ChangeLog
+
+# Generate the ChangeLog file (with all entries since the switch to git)
+# and insert it into the directory we're about to use to create a tarball.
+gen_start_date = 2009-07-04
+.PHONY: gen-ChangeLog
+gen-ChangeLog:
+	if test -d .git; then					\
+	  $(top_srcdir)/build-aux/gitlog-to-changelog		\
+	    --since=$(gen_start_date) > $(distdir)/cl-t;	\
+	  rm -f $(distdir)/ChangeLog;				\
+	  mv $(distdir)/cl-t $(distdir)/ChangeLog;		\
+	fi

autogen.sh

@@ -54,6 +54,9 @@ if test -z "$*"; then
         echo "to pass any to it, please specify them on the $0 command line."
 fi
 
+# Automake requires that ChangeLog exist.
+touch ChangeLog
+
 autopoint --force
 #rm -rf m4
 libtoolize --copy --force

bootstrap

@@ -78,6 +78,7 @@ getaddrinfo
 gethostname
 getpass
 gettext
+gitlog-to-changelog
 gnumakefile
 inet_pton
 ioctl

build-aux/.gitignore

@@ -10,3 +10,4 @@ mkinstalldirs
 mktempd
 /useless-if-before-free
 /vc-list-files
+/gitlog-to-changelog