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: I9f2e7cfd93ee0b13d064c606a20378c1ea01400e

debian/control

@@ -7,7 +7,8 @@ Build-Depends: debhelper (>= 9),
                dh-systemd (>= 1.5),
                autotools-dev,
                pkg-config,
-               libosmocore-dev (>= 0.10.1)
+               libosmocore-dev (>= 0.10.1),
+               osmo-gsm-manuals-dev
 Standards-Version: 3.9.8
 Homepage: http://osmocom.org/projects/osmopcu
 Vcs-Git: git://git.osmocom.org/osmo-pcu
@@ -35,3 +36,12 @@ Description: Debug symbols for the Osmocom GPRS/EDGE Packet Control Unit (PCU)
  networks.  OsmoPCU is the Osmcoom implementation of this network
  element. It interfaces to osmo-bts via the PCU socket of OsmoBTS
  and via Gb (NS-over-IP) interface with the SGSN such as OsmoSGSN.
+
+Package: osmo-pcu-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-pcu-doc.install

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

debian/rules

@@ -24,4 +24,8 @@ override_dh_auto_test:
 	dh_auto_test || (find . -name testsuite.log -exec cat {} \; ; false)
 
 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

@@ -16,5 +16,6 @@ if BUILD_MANUALS
   VTY_REFERENCE = osmopcu-vty-reference.xml
   include $(OSMO_GSM_MANUALS_DIR)/build/Makefile.vty-reference.inc
 
+  OSMO_REPOSITORY = osmo-pcu
   include $(OSMO_GSM_MANUALS_DIR)/build/Makefile.common.inc
 endif