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: I8466713a8d414ea56ca24f6f7119338ad2b98ce5

debian/control

@@ -7,7 +7,8 @@ Build-Depends: debhelper (>=9),
                pkg-config,
                autotools-dev,
                libosmocore-dev,
-               libosmo-netif-dev
+               libosmo-netif-dev,
+               osmo-gsm-manuals-dev
 Standards-Version: 3.9.8
 Vcs-Git: git://git.osmocom.org/osmo-mgw.git
 Vcs-Browser: https://git.osmocom.org/osmo-mgw/
@@ -33,3 +34,12 @@ Architecture: any
 Multi-Arch: same
 Depends: libosmo-mgcp-client5 (= ${binary:Version}), ${misc:Depends}
 Description: libosmo-mgcp-client: Osmocom's Media Gateway Control Protocol client utilities
+
+Package: osmo-mgw-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-mgw-doc.install

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

debian/rules

@@ -30,6 +30,10 @@ 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
 
 # See https://www.debian.org/doc/manuals/developers-reference/best-pkging-practices.html#bpp-dbg

doc/manuals/Makefile.am

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