debian: create -doc subpackage with pdf manuals

I have verified, that the resulting debian packages build in my own OBS
namespace (see the -doc packages):
https://download.opensuse.org/repositories/home:/osmith42/Debian_9.0/all/
https://build.opensuse.org/project/show/home:osmith42

Depends: Ib7251cca9116151e473798879375cd5eb48ff3ad (osmo-ci)
Related: OS#3899
Change-Id: I30df67b1c31f07e85002da4c2c75afb67ba529d2

debian/control

@@ -9,7 +9,8 @@ Build-Depends: debhelper (>= 7.0.0~),
                libsofia-sip-ua-glib-dev,
                libsofia-sip-ua-dev,
                dh-systemd (>= 1.5),
-               dh-autoreconf
+               dh-autoreconf,
+               osmo-gsm-manuals-dev
 Standards-Version: 3.8.4
 Homepage: https://osmocom.org/projects/osmo-sip-conector/wiki
 Vcs-Git: git://git.osmocom.org/osmo-sip-connector.git
@@ -28,3 +29,12 @@ Priority: extra
 Depends: osmo-sip-connector (= ${binary:Version}), ${misc:Depends}
 Description: Debug symbols for the osmo-sip-connector
  Make debugging possible
+
+Package: osmo-sip-connector-doc
+Architecture: all
+Section: doc
+Priority: optional
+Depends: ${misc:Depends}
+Description: ${misc:Package} PDF documentation
+ Various manuals: user manual, VTY reference manual and/or
+ protocol/interface manuals.

debian/osmo-sip-connector-doc.install

@@ -0,0 +1 @@
+usr/share/doc/osmo-sip-connector-doc/*.pdf

debian/rules

@@ -15,4 +15,8 @@ override_dh_strip:
 	dh_strip --dbg-package=osmo-sip-connector-dbg
 
 override_dh_auto_configure:
-	dh_auto_configure -- --with-systemdsystemunitdir=/lib/systemd/system
+	dh_auto_configure -- --with-systemdsystemunitdir=/lib/systemd/system --enable-manuals
+
+# Don't create .pdf.gz files (barely saves space and they can't be opened directly by most pdf readers)
+override_dh_compress:
+	dh_compress -X.pdf

doc/manuals/Makefile.am

@@ -12,5 +12,6 @@ if BUILD_MANUALS
   VTY_REFERENCE = osmosipconnector-vty-reference.xml
   include $(OSMO_GSM_MANUALS_DIR)/build/Makefile.vty-reference.inc
 
+  OSMO_REPOSITORY = osmo-sip-connector
   include $(OSMO_GSM_MANUALS_DIR)/build/Makefile.common.inc
 endif