tests: Split SCTP tests to its own file and run them conditionally

Some systmes (like the ones available in OBS) don't support creating
SCTP sockets, so we need to skip those tests there.

Change-Id: I1d16280674625877ec22cc60cbc5deb67868a656
diff --git a/tests/socket/socket_sctp_test.err b/tests/socket/socket_sctp_test.err
new file mode 100644
index 0000000..996d092
--- /dev/null
+++ b/tests/socket/socket_sctp_test.err
@@ -0,0 +1,8 @@
+invalid: you have to specify either BIND or CONNECT flags
+Invalid v4 vs v6 in local vs remote addresses
+Invalid v4 vs v6 in local vs remote addresses
+invalid: you have to specify either BIND or CONNECT flags
+Invalid v4 vs v6 in local vs remote addresses
+Invalid v4 vs v6 in local vs remote addresses
+getaddrinfo(::1, 0) failed: Address family for hostname not supported
+getaddrinfo(127.0.0.1, 0) failed: Address family for hostname not supported