tests/gb: Add test for GPRS NS protocol

This tests the connection establishment by directly calling
gprs_ns_rcvmsg() and printing the resulting messages and the
NS-VC list.
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 97d0adc..0685832 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -106,6 +106,12 @@
 AT_CHECK([$abs_top_builddir/tests/vty/vty_test], [0], [expout], [ignore])
 AT_CLEANUP
 
+AT_SETUP([gprs-ns])
+AT_KEYWORDS([gprs-ns])
+cat $abs_srcdir/gb/gprs_ns_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/gb/gprs_ns_test], [0], [expout], [ignore])
+AT_CLEANUP
+
 AT_SETUP([bssgp-fc])
 AT_KEYWORDS([bssgp-fc])
 cat $abs_srcdir/gb/bssgp_fc_tests.ok > expout