Increase dpkg manpage determinism

Makefile

@@ -171,6 +171,7 @@ DOCS=edge.8.gz supernode.1.gz n2n.7.gz
 BUILD_DEP:=\
 	autoconf \
 	build-essential \
+	dh-strip-nondeterminism \
 	flake8 \
 	gcovr \
 	libcap-dev \

packages/debian/debian/rules.in

@@ -12,6 +12,9 @@
 # http://www.tin.org/bin/man.cgi?section=7&topic=debhelper
 #
 
+# Not needed for newer debhelper versions, but some builders run older ones
+export GZIP=-n
+
 package=@APP@
 
 build: build-stamp
@@ -44,6 +47,7 @@ binary-arch: build install
 	dh_installman
 	dh_strip
 	dh_compress
+	dh_strip_nondeterminism
 	dh_fixperms
 	dh_installdeb
 	cp -r n2n debian