jenkins: build from new osmo-{msc,bsc,mgw,sgsn} repositories

The idea is to build each binary separately: even though osmo-msc requires
libosmo-sccp, which already includes the osmo-stp binary, we still want
osmo-stp to be built from a separate script. The reason: to track down
regressions, we can change the versions each binary is built from separately.
The additional build effort and jenkins script multitude is acceptable.

Change-Id: I194ad5169dbe013c8e1cf9d631033cb2576744dd
diff --git a/src/osmo_gsm_tester/osmo_mgcpgw.py b/src/osmo_gsm_tester/osmo_mgcpgw.py
index db41dff..93c3a7c 100644
--- a/src/osmo_gsm_tester/osmo_mgcpgw.py
+++ b/src/osmo_gsm_tester/osmo_mgcpgw.py
@@ -40,7 +40,7 @@
         self.log('Starting osmo-mgcpgw')
         self.run_dir = util.Dir(self.suite_run.get_test_run_dir().new_dir(self.name()))
         self.configure()
-        inst = util.Dir(os.path.abspath(self.suite_run.trial.get_inst('osmo-msc')))
+        inst = util.Dir(os.path.abspath(self.suite_run.trial.get_inst('osmo-mgw')))
         binary = inst.child('bin', 'osmo-bsc_mgcp')
         if not os.path.isfile(binary):
             raise RuntimeError('Binary missing: %r' % binary)