Better error-message handling for SCTP

[spencersevilla]

In mme.conf, if "MME_IPV4_ADDRESS_FOR_S1_MME" is set to an IP address that the host does not own, the MME will crash with a very unhelpful message ("Failed to create new SCTP listener") as displayed below. We should handle this condition better, either by (1) checking for IP address ownership and failing gracefully; (2) printing out a more verbose error message; or (3) just changing the current error message to be more descriptive.

Backtrace below:

# mme
Initializing shared logging
Initializing shared logging Done
Initializing OAI Logging
Initializing OAI logging Done
Parsing configuration file found S1-MME: 192.168.0.4/24 on enp4s0
Parsing configuration file found S11: 127.0.0.20/8 on lo
Parsing configuration file found S-GW S11: 127.0.0.1
Creating queue of message of size 128
Creating queue of message of size 256
Creating queue of message of size 256
Creating queue of message of size 256
Creating queue of message of size 256
Creating queue of message of size 256
Creating queue of message of size 256
Creating queue of message of size 256
Creating queue of message of size 256
Creating queue of message of size 256
Creating queue of message of size 256
Creating queue of message of size 1024
Creating queue of message of size 1024
Creating queue of message of size 256
Initializing MSC logs
Initializing MSC logs Done

Assertion (0) failed!
In sctp_intertask_interface()
/home/vagrant/openair-cn/src/sctp/sctp_primitives_server.c:643
Failed to create new SCTP listener

Will Intentionaly raise SEGFAULT to be catched by GDB!
Obtained 4 stack frames.
mme(display_backtrace+0x28) [0x55d93695ecf0]
mme(+0x110c5d) [0x55d936935c5d]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x74a4) [0x7f967fc5f4a4]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x3f) [0x7f967dac6d0f]