Debian/Ubuntu: default debhelper compat level increased to 11.

This is the version installed out of the box on Ubuntu 18.04 "bionic"
which is the oldest one from supported distros.

While here:
 - Standards-Version increased to 4.1.4 (matches Ubuntu 18.04 as well),
 - explicitly added systemd service for nginx-debug binary (previously
it was installed by dh_systemd_enable from modified init script).

debian/Makefile

diff --git a/debian/Makefile b/debian/Makefile
index c49c5c3..0496c49 100644
--- a/debian/Makefile
+++ b/debian/Makefile
@@ -155,7 +155,7 @@
 	mkdir -p debuild-base/$(SRCDIR)/debian ; \
 	mkdir -p debuild-base/$(SRCDIR)/debian/source ; \
 	echo "3.0 (quilt)" > debuild-base/$(SRCDIR)/debian/source/format ; \
-	echo "9" > debuild-base/$(SRCDIR)/debian/compat ; \
+	echo "11" > debuild-base/$(SRCDIR)/debian/compat ; \
 	for patch in `find $(CONTRIB)/src/nginx$(BASE_SUFFIX)/ -type f -name '*.patch' -printf "%f\n" | sort`; do \
 		mkdir -p debuild-base/$(SRCDIR)/debian/patches ; \
 		echo $$patch >> debuild-base/$(SRCDIR)/debian/patches/series ; \
@@ -260,7 +260,7 @@
 	mkdir -p $${builddir}/$(SRCDIR)/debian/extra ; \
 	mkdir -p $${builddir}/$(SRCDIR)/debian/source ; \
 	echo "3.0 (quilt)" > $${builddir}/$(SRCDIR)/debian/source/format ; \
-	echo "9" > $${builddir}/$(SRCDIR)/debian/compat ; \
+	echo "11" > $${builddir}/$(SRCDIR)/debian/compat ; \
 	for src in $(MODULE_SOURCES_$(call modname, $*)); do \
 		tar -C $${builddir}/$(SRCDIR)/debian/extra -xvf $(CONTRIB)/tarballs/$${src} ; \
 		sn=`echo $${src} | sed -e 's/-[0-9].*$$//'` ; \

debian/nginx-module.control.in

diff --git a/debian/nginx-module.control.in b/debian/nginx-module.control.in
index 6b96848..958301f 100644
--- a/debian/nginx-module.control.in
+++ b/debian/nginx-module.control.in
@@ -2,14 +2,14 @@
 Section: httpd
 Priority: optional
 Maintainer: %%PACKAGE_VENDOR%%
-Build-Depends: debhelper (>= 9~),
+Build-Depends: debhelper (>= 11),
                dpkg-dev (>= 1.16.1~),
                quilt (>= 0.46-7~),
                lsb-release,
                libssl-dev (>= 1.0.1),
                libpcre3-dev,
                zlib1g-dev%%MODULE_BUILD_DEPENDS%%
-Standards-Version: 3.9.8.0
+Standards-Version: 4.1.4
 Homepage: %%MODULE_PACKAGE_URL%%
 
 Package: nginx-module-%%MODULE%%

debian/nginx-plus-module.control.in

diff --git a/debian/nginx-plus-module.control.in b/debian/nginx-plus-module.control.in
index 5f41043..ad9c109 100644
--- a/debian/nginx-plus-module.control.in
+++ b/debian/nginx-plus-module.control.in
@@ -2,14 +2,14 @@
 Section: httpd
 Priority: optional
 Maintainer: %%PACKAGE_VENDOR%%
-Build-Depends: debhelper (>= 9~),
+Build-Depends: debhelper (>= 11),
                dpkg-dev (>= 1.16.1~),
                quilt (>= 0.46-7~),
                lsb-release,
                libssl-dev (>= 1.0.1),
                libpcre3-dev,
                zlib1g-dev%%MODULE_BUILD_DEPENDS%%
-Standards-Version: 3.9.8.0
+Standards-Version: 4.1.4
 Homepage: %%MODULE_PACKAGE_URL%%
 
 Package: nginx-plus-module-%%MODULE%%

debian/nginx.control.in

diff --git a/debian/nginx.control.in b/debian/nginx.control.in
index 439dd7f..961814f 100644
--- a/debian/nginx.control.in
+++ b/debian/nginx.control.in
@@ -2,15 +2,14 @@
 Section: httpd
 Priority: optional
 Maintainer: %%PACKAGE_VENDOR%%
-Build-Depends: debhelper (>= 9~),
-               dh-systemd | debhelper (>= 9.20160709),
+Build-Depends: debhelper (>= 11),
                dpkg-dev (>= 1.16.1~),
                quilt (>= 0.46-7~),
                lsb-release,
                libssl-dev (>= 0.9.7),
                libpcre3-dev,
                zlib1g-dev
-Standards-Version: 3.9.8.0
+Standards-Version: 4.1.4
 Homepage: https://nginx.org
 
 Package: nginx

debian/nginx.rules.in

diff --git a/debian/nginx.rules.in b/debian/nginx.rules.in
index 7d963c3..b09e62e 100755
--- a/debian/nginx.rules.in
+++ b/debian/nginx.rules.in
@@ -106,14 +106,14 @@
 		-e 's/%%DEFAULTSTART%%/2 3 4 5/g' \
 		-e 's/%%DEFAULTSTOP%%/0 1 6/g' \
 		< debian/nginx.init.in > debian/nginx.init
-	dh_installinit -i -pnginx --no-restart-on-upgrade --no-start --name=nginx
-	dh_systemd_enable -pnginx --name=nginx nginx.service
+	dh_installinit -i -pnginx --no-stop-on-upgrade --no-start --name=nginx
+	dh_installsystemd -i -pnginx --name=nginx nginx.service
 	sed -e 's/%%PROVIDES%%/nginx-debug/g' \
 		-e 's/%%DEFAULTSTART%%//g' \
 		-e 's/%%DEFAULTSTOP%%/0 1 2 3 4 5 6/g' \
 		< debian/nginx.init.in > debian/nginx-debug.init
-	dh_installinit -i -pnginx --no-restart-on-upgrade --no-start --noscripts --name=nginx-debug
-	dh_systemd_enable -pnginx --name=nginx-debug --no-enable nginx-debug.service
+	dh_installinit -i -pnginx --no-stop-on-upgrade --no-start --noscripts --name=nginx-debug
+	dh_installsystemd -i -pnginx --name=nginx-debug --no-enable nginx-debug.service
 	dh_installlogrotate -i -pnginx --name=nginx
 
 binary-arch: install build-dbg