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
9 files changed