[configure] Generate sha256sum and GPG-sign it

Makefile.am

@@ -29,8 +29,11 @@ MAINTAINERCLEANFILES = \
 	$(srcdir)/ChangeLog \
 	`find "$(srcdir)" -type f -name Makefile.in -print`
 
-CHANGELOG_RANGE =
 
+#
+# ChangeLog generation
+#
+CHANGELOG_RANGE =
 ChangeLog: $(srcdir)/ChangeLog
 $(srcdir)/ChangeLog:
 	$(AM_V_GEN) if test -d "$(srcdir)/.git"; then \
@@ -48,4 +51,28 @@ $(srcdir)/ChangeLog:
 .PHONY: $(srcdir)/ChangeLog
 
 
+#
+# Release engineering
+#
+
+TAR_OPTIONS = --owner=0 --group=0
+dist-hook: dist-clear-sticky-bits
+# Clean up any sticky bits we may inherit from parent dir
+dist-clear-sticky-bits:
+	chmod -R a-s $(distdir)
+
+
+tar_file = $(PACKAGE_TARNAME)-$(VERSION).tar.bz2
+sha256_file = $(tar_file).sha256
+gpg_file = $(sha256_file).asc
+$(sha256_file): $(tar_file)
+	sha256sum $^ > $@
+$(gpg_file): $(sha256_file)
+	@echo "Please enter your GPG password to sign the checksum."
+	gpg --armor --sign $^
+
+release-files: $(tar_file) $(sha256_file) $(gpg_file)
+
+
+
 -include $(top_srcdir)/git.mk