deb/rpm: build with --enable-gtp-linux

Allow optional use of the GTP kernel module.

Related: OS#3208
Change-Id: Ic001ec6c5ec9887706a5b27f2a48cd61942ab4ee
diff --git a/contrib/osmo-ggsn.spec.in b/contrib/osmo-ggsn.spec.in
index 4e8b11e..83a1ca7 100644
--- a/contrib/osmo-ggsn.spec.in
+++ b/contrib/osmo-ggsn.spec.in
@@ -34,6 +34,7 @@
 BuildRequires:  pkgconfig(libosmocore) >= 1.1.0
 BuildRequires:  pkgconfig(libosmoctrl) >= 1.1.0
 BuildRequires:  pkgconfig(libosmovty) >= 1.1.0
+BuildRequires:  pkgconfig(libgtpnl) >= 1.2.0
 Obsoletes:      openggsn
 %{?systemd_requires}
 
@@ -69,6 +70,7 @@
 echo "%{version}" >.tarball-version
 autoreconf -fi
 %configure \
+  --enable-gtp-linux \
   --disable-static \
   --docdir="%{_docdir}/%{name}" \
   --with-systemdsystemunitdir=%{_unitdir} \