Generate ChangeLog from git in make dist

Archive the existing ChangeLog to ChangeLog.libffi-3.1

ChangeLog.libffi-3.1

@@ -1,3 +1,9 @@
+2014-03-16  Josh Triplett  <josh@joshtriplett.org>
+
+	* ChangeLog: Archive to ChangeLog.libffi-3.1 and delete.  Future
+	changelogs will come from git, with autogenerated snapshots shipped in
+	distributed tarballs.
+
 2014-03-16  Josh Triplett  <josh@joshtriplett.org>
 
 	Add support for stdcall, thiscall, and fastcall on non-Windows

Makefile.am

@@ -50,7 +50,7 @@ EXTRA_DIST = LICENSE ChangeLog.v1 ChangeLog.libgcj configure.host	\
 	 m4/ltversion.m4 src/arm/gentramp.sh src/debug.c msvcc.sh	\
 	 generate-darwin-source-and-headers.py				\
 	 libffi.xcodeproj/project.pbxproj src/arm/trampoline.S		\
-	 libtool-ldflags
+	 libtool-ldflags ChangeLog.libffi-3.1
 
 info_TEXINFOS = doc/libffi.texi
 
@@ -247,3 +247,5 @@ libffi_la_LDFLAGS = -no-undefined -version-info `grep -v '^\#' $(srcdir)/libtool
 AM_CPPFLAGS = -I. -I$(top_srcdir)/include -Iinclude -I$(top_srcdir)/src
 AM_CCASFLAGS = $(AM_CPPFLAGS)
 
+dist-hook:
+	if [ -d $(top_srcdir)/.git ] ; then git -C $(top_srcdir) log --no-decorate ; else echo 'See git log for history.' ; fi > $(distdir)/ChangeLog

README

@@ -1,7 +1,7 @@
 Status
 ======
 
-libffi-3.0.14 was released on TBD.  Check the libffi web
+libffi-3.1 was released on TBD.  Check the libffi web
 page for updates: <URL:http://sourceware.org/libffi/>.
 
 
@@ -170,9 +170,10 @@ To install the library and header files, type "make install".
 History
 =======
 
-See the ChangeLog files for details.
+See the git log for details.
 
-3.0.14 TBD
+3.1 TBD
+	Archive off the manually maintained ChangeLog in favor of git log.
         Add AArch64 (ARM64) iOS support.
         Add Nios II support.
         Add m88k and DEC VAX support.