simtrace2-sniff: Fix build with released libosmocore versions

There's still no released libosmocore defining the GSMTAP_TYPE_SIM
sub-types (Change-Id: I5bd0dff5a4a90cfe96d9c4f3dec6657e1d85bf7a
dated Jul 26, 2018).

Let's make sure users don't need an unreleased version of the library
if it's only about a few #defines that we can just copy here for
backwards compatibility.

Change-Id: I2fd9e14873711d60f194bb404420bbfbb0a00f48
diff --git a/host/simtrace2-sniff.c b/host/simtrace2-sniff.c
index 368ae60..dddf5cf 100644
--- a/host/simtrace2-sniff.c
+++ b/host/simtrace2-sniff.c
@@ -51,6 +51,19 @@
 #include <osmocom/sim/class_tables.h>
 #include <osmocom/sim/sim.h>
 
+/* as of August 26, 2018 we don't have any released libosmocore version which includes those
+ * definitions yet.  Let's ensure some backwards compatibility: */
+#ifndef GSMTAP_SIM_APDU
+#define GSMTAP_SIM_APDU		0x00 /* APDU data (complete APDU) */
+#define GSMTAP_SIM_ATR		0x01 /* card ATR data */
+#define GSMTAP_SIM_PPS_REQ		0x02 /* PPS request data */
+#define GSMTAP_SIM_PPS_RSP		0x03 /* PPS response data */
+#define GSMTAP_SIM_TPDU_HDR		0x04 /* TPDU command header */
+#define GSMTAP_SIM_TPDU_CMD		0x05 /* TPDU command body */
+#define GSMTAP_SIM_TPDU_RSP		0x06 /* TPDU response body */
+#define GSMTAP_SIM_TPDU_SW		0x07 /* TPDU response trailer */
+#endif
+
 /* transport to a SIMtrace device */
 struct st_transport {
 	/* USB */