PCU sock path / cleanup
Make sure unix socket paths are placed in the run dir and cleaned up properly.
On the main unit for some reason there was a /tmp/pcu_bts unix socket left behind, blocking newer test runs.
It's a bit confusing to me why the OsmoNITB fails with error output about the BTS <-> PCU socket, but this is the output:
01:04:24 run osmo-nitb_10.42.42.1(pid=8192): stderr: | (launched: 2017-05-27_01:04:24) | 20170527010424567 <001e> telnet_interface.c:95 telnet at 10.42.42.1 4242 | 20170527010424567 <0020> input/ipaccess.c:847 enabling ipaccess BSC mode on 10.42.42.1 with OML 3002 and RSL 3003 TCP ports | 20170527010424568 <001d> pcu_sock.c:702 Could not create unix socket: Address already in use | 20170527010424568 <0005> bsc_init.c:548 PCU L1 socket failed for bts 0 | Reading config failed. Exiting.
When I removed /tmp/pcu_bts, things worked again.