Make manpages in a conatiner.

Signed-off-by: Daniel Nephin <dnephin@docker.com>
(cherry picked from commit 7004f219f5d0fe99de0dadf319381d224866eb7c)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
diff --git a/hack/make/build-deb b/hack/make/build-deb
index 41b2eda..98fc007 100644
--- a/hack/make/build-deb
+++ b/hack/make/build-deb
@@ -35,7 +35,7 @@
 	debDate="$(date --rfc-2822)"
 
 	# if go-md2man is available, pre-generate the man pages
-	./man/generate.sh || true
+	make manpages || true
 	# TODO decide if it's worth getting go-md2man in _each_ builder environment to avoid this
 
 	builderDir="contrib/builder/deb/${PACKAGE_ARCH}"
diff --git a/hack/make/build-rpm b/hack/make/build-rpm
index 995dcd8..5d61dc9 100644
--- a/hack/make/build-rpm
+++ b/hack/make/build-rpm
@@ -51,7 +51,7 @@
 	rpmDate="$(date +'%a %b %d %Y')"
 
 	# if go-md2man is available, pre-generate the man pages
-	./man/generate.sh || true
+	make manpages || true
 	# TODO decide if it's worth getting go-md2man in _each_ builder environment to avoid this
 
 	# Convert the CHANGELOG.md file into RPM changelog format
diff --git a/hack/make/ubuntu b/hack/make/ubuntu
index 7033dd5..8de5d9c 100644
--- a/hack/make/ubuntu
+++ b/hack/make/ubuntu
@@ -60,7 +60,7 @@
 	cp contrib/completion/fish/docker.fish "$DIR/etc/fish/completions/"
 
 	# Include man pages
-	man/generate.sh
+	make manpages
 	manRoot="$DIR/usr/share/man"
 	mkdir -p "$manRoot"
 	for manDir in man/man?; do