emu: Send a static GPRS ATTACH request and wait for the reply.

This will send a static message. It will trigger the GMM code
on the SGSN and might ask us for the IMEI/IMSI or send us an
accept. As we are not replying at all the SGSN needs to send new
requests and we can observe if the sequence number is increasing
like it should.
diff --git a/tests/emu/pcu_emu.cpp b/tests/emu/pcu_emu.cpp
index f78285d..337c0c8 100644
--- a/tests/emu/pcu_emu.cpp
+++ b/tests/emu/pcu_emu.cpp
@@ -36,6 +36,8 @@
 struct gprs_rlcmac_bts *gprs_rlcmac_bts;
 int16_t spoof_mnc = 0, spoof_mcc = 0;
 
+extern void test_replay_gprs_attach(struct gprs_bssgp_pcu *pcu);
+
 struct gprs_rlcmac_bts *create_bts()
 {
 	struct gprs_rlcmac_bts *bts;
@@ -62,9 +64,10 @@
 	return bts;
 }
 
-static void bvci_unblocked(struct gprs_bssgp_pcu *pci)
+static void bvci_unblocked(struct gprs_bssgp_pcu *pcu)
 {
 	printf("BVCI unblocked. We can begin with test cases.\n");
+	test_replay_gprs_attach(pcu);
 }
 
 void create_and_connect_bssgp(struct gprs_rlcmac_bts *bts,