implement simpler ChangeLog generation for source tarballs

We used ax_generate_changelog which works great. But it made our
makefile require GNU make, which was causing annoyance on bsd systems.

ChangeLog

@@ -1,2 +0,0 @@
-The ChangeLog is auto-generated when releasing.
-If you are seeing this, use 'git log' for a detailed list of changes.

Makefile.am

@@ -119,7 +119,7 @@ googleinclude_HEADERS =				\
 # Add your documentation files (in doc/) in addition to these
 # top-level boilerplate files.  Also add a TODO file if you have one.
 # We'll add to this later, on a library-by-library basis
-dist_doc_DATA = AUTHORS COPYING ChangeLog INSTALL NEWS README README_windows.txt \
+dist_doc_DATA = AUTHORS COPYING INSTALL NEWS README README_windows.txt \
                 TODO ChangeLog.old
 
 # The libraries (.so's) you want to install
@@ -1442,10 +1442,15 @@ libprofiler.pc: libtcmalloc.pc
 libtool: $(LIBTOOL_DEPS)
 	$(SHELL) ./config.status --recheck
 
-@GENERATE_CHANGELOG_RULES@
+$(top_distdir)/ChangeLog:
+	if test ! -f $(top_srcdir)/ChangeLog ; \
+	  then git --git-dir=$(top_srcdir)/.git --work-tree=$(top_srcdir) \
+	        log --stat -M -C --name-status --no-color \
+	       | fmt --split-only >$(top_distdir)/ChangeLog; \
+	  else cp $(top_srcdir)/ChangeLog $(top_distdir)/ChangeLog; fi
 
 # Windows wants write permission to .vcxproj files and maybe even sln files.
-dist-hook: dist-ChangeLog
+dist-hook: $(top_distdir)/ChangeLog
 	test -e "$(distdir)/vsprojects" \
 	   && chmod -R u+w $(distdir)/*.sln $(distdir)/vsprojects/
 

configure.ac

@@ -20,7 +20,7 @@ AC_SUBST(TCMALLOC_AND_PROFILER_SO_VERSION)
 AC_CONFIG_SRCDIR(README)
 AC_CONFIG_MACRO_DIR([m4])
 AC_CANONICAL_HOST
-AM_INIT_AUTOMAKE([dist-zip])
+AM_INIT_AUTOMAKE([dist-zip foreign])
 AC_CONFIG_HEADERS([src/config.h])
 
 AM_MAINTAINER_MODE()
@@ -33,8 +33,6 @@ AC_SUBST(TC_VERSION_MINOR)
 AC_SUBST(TC_VERSION_PATCH)
 AC_SUBST(PACKAGE_STRING)
 
-AX_GENERATE_CHANGELOG
-
 # The user can choose not to compile in the heap-profiler, the
 # heap-checker, or the cpu-profiler.  There's also the possibility
 # for a 'fully minimal' compile, which leaves out the stacktrace

m4/ax_generate_changelog.m4

@@ -1,99 +0,0 @@
-# ===========================================================================
-#   http://www.gnu.org/software/autoconf-archive/ax_generate_changelog.html
-# ===========================================================================
-#
-# SYNOPSIS
-#
-#   AX_GENERATE_CHANGELOG()
-#
-# DESCRIPTION
-#
-#   Builds a rule for generating a ChangeLog file from version control
-#   system commit messages.  Currently, the only supported VCS is git, but
-#   support for others could be added in future.
-#
-#   Defines GENERATE_CHANGELOG_RULES which should be substituted in your
-#   Makefile.
-#
-#   Usage example:
-#
-#   configure.ac:
-#
-#     AX_GENERATE_CHANGELOG
-#
-#   Makefile.am:
-#
-#     @GENERATE_CHANGELOG_RULES@
-#     CHANGELOG_START = 0.2.3^
-#     dist-hook: dist-ChangeLog
-#
-#   ChangeLog (stub committed to VCS):
-#
-#     The ChangeLog is auto-generated when releasing.
-#     If you are seeing this, use 'git log' for a detailed list of changes.
-#
-#   This results in a "dist-ChangeLog" rule being added to the Makefile.
-#   When run, "dist-ChangeLog" will generate a ChangeLog in the
-#   $(top_distdir), using $(CHANGELOG_GIT_FLAGS) to format the output from
-#   "git log" being run in $(CHANGELOG_GIT_DIR).
-#
-#   Unless Automake is initialised with the 'foreign' option, a dummy
-#   ChangeLog file must be committed to VCS in $(top_srcdir), containing the
-#   text above (for example).  It will be substituted by the automatically
-#   generated ChangeLog during "make dist".
-#
-# LICENSE
-#
-#   Copyright (c) 2015 David King <amigadave@amigadave.com>
-#   Copyright (c) 2015 Philip Withnall <philip.withnall@collabora.co.uk>
-#
-#   Copying and distribution of this file, with or without modification, are
-#   permitted in any medium without royalty provided the copyright notice
-#   and this notice are preserved.  This file is offered as-is, without any
-#   warranty.
-
-#serial 1
-
-AC_DEFUN([AX_GENERATE_CHANGELOG],[
-	# Find git, defaulting to the 'missing' script so the user gets a nice
-	# message if git is missing, rather than a plain 'command not found'.
-	AC_PATH_PROG([GIT],[git],[${am_missing_run}git])
-	AC_SUBST([GIT])
-
-	# Build the ChangeLog rules.
-	m4_pattern_allow([AM_V_GEN])
-GENERATE_CHANGELOG_RULES='
-# Generate ChangeLog
-#
-# Optional:
-#  - CHANGELOG_START: git commit ID or tag name to output changelogs from
-#    (exclusive). (Default: include all commits)
-#  - CHANGELOG_GIT_FLAGS: General flags to pass to git-log when generating the
-#    ChangeLog. (Default: various)
-#  - CHANGELOG_GIT_DIR: .git directory to use. (Default: $(top_srcdir)/.git)
-
-# git-specific
-CHANGELOG_GIT_FLAGS ?= --stat -M -C --name-status --no-color
-CHANGELOG_GIT_DIR ?= $(top_srcdir)/.git
-
-ifeq ($(CHANGELOG_START),)
-CHANGELOG_GIT_RANGE =
-else
-CHANGELOG_GIT_RANGE = $(CHANGELOG_START)..
-endif
-
-# Generate a ChangeLog in $(top_distdir)
-dist-ChangeLog:
-	$(AM_V_GEN)if $(GIT) \
-		--git-dir=$(CHANGELOG_GIT_DIR) --work-tree=$(top_srcdir) log \
-		$(CHANGELOG_GIT_FLAGS) $(CHANGELOG_GIT_RANGE) \
-		| fmt --split-only >.ChangeLog.tmp; \
-	then mv -f .ChangeLog.tmp "$(top_distdir)/ChangeLog"; \
-	else rm -f .ChangeLog.tmp; exit 1; fi
-
-.PHONY: dist-ChangeLog
-'
-
-	AC_SUBST([GENERATE_CHANGELOG_RULES])
-	m4_ifdef([_AM_SUBST_NOTMAKE], [_AM_SUBST_NOTMAKE([GENERATE_CHANGELOG_RULES])])
-])