debian: Fix dependencies

The dependecies do not match the current package names or are
missing:

Build-Depends:
  - renamed libgtp-dev -> libgtp0-dev
  - added   libosmo-netif-dev

Depends:
  - renamed libgtp     -> libgtp0

Other run time dependencies might still be missing and have to be
installed manually.

This is taken from Holger's e744ebd17c3761b5cad81d718d0349f2f820ec66.
In addition, the build-dependency on libgtp-dev is replaced by
libgtp0-dev.

debian/control

@@ -2,7 +2,7 @@ Source: openbsc
 Section: net
 Priority: optional
 Maintainer: Harald Welte <laforge@gnumonks.org>
-Build-Depends: debhelper (>= 7.0.0~), autotools-dev, pkg-config, libgtp-dev, libosmocore-dev, libosmo-sccp-dev, libdbi0-dev, dh-autoreconf, libosmo-abis-dev, libdbd-sqlite3
+Build-Depends: debhelper (>= 7.0.0~), autotools-dev, pkg-config, libgtp0-dev, libosmocore-dev, libosmo-sccp-dev, libdbi0-dev, dh-autoreconf, libosmo-abis-dev, libosmo-netif-dev, libdbd-sqlite3
 Standards-Version: 3.8.4
 Homepage: http://openbsc.osmocom.org/
 Vcs-Git: git://bs11-abis.gnumonks.org/openbsc.git
@@ -34,7 +34,7 @@ Description: Command line utilities for Siemens BS-11 BTS
 
 Package: osmocom-sgsn
 Architecture: any
-Depends: ${shlibs:Depends}, ${misc:Depends}, libosmocore, libgtp
+Depends: ${shlibs:Depends}, ${misc:Depends}, libosmocore, libgtp0
 Description: Osmocom Serving GPRS Support Node
  SGSN implementation.