use new libosmocore gsm_23_003.h for IMEI/IMSI length

... rather than our private definitions everwhere.  As an added benefit,
gprs_gsup_messages.h is now free of any header dependencies within
openbsc.
diff --git a/openbsc/src/gprs/gprs_gsup_messages.c b/openbsc/src/gprs/gprs_gsup_messages.c
index 0b1dc9b..b3c8dab 100644
--- a/openbsc/src/gprs/gprs_gsup_messages.c
+++ b/openbsc/src/gprs/gprs_gsup_messages.c
@@ -31,6 +31,7 @@
 
 #include <osmocom/gsm/tlv.h>
 #include <osmocom/core/msgb.h>
+#include <osmocom/gsm/gsm48_ie.h>
 
 #include <stdint.h>
 
diff --git a/openbsc/src/gprs/gprs_subscriber.c b/openbsc/src/gprs/gprs_subscriber.c
index 5b0bf39..648f912 100644
--- a/openbsc/src/gprs/gprs_subscriber.c
+++ b/openbsc/src/gprs/gprs_subscriber.c
@@ -757,8 +757,9 @@
 	}
 
 	if (strcpy(subscr->equipment.imei, mmctx->imei) != 0) {
-		strncpy(subscr->equipment.imei, mmctx->imei, GSM_IMEI_LENGTH-1);
-		subscr->equipment.imei[GSM_IMEI_LENGTH-1] = 0;
+		strncpy(subscr->equipment.imei, mmctx->imei,
+			sizeof(subscr->equipment.imei)-1);
+		subscr->equipment.imei[sizeof(subscr->equipment.imei)-1] = 0;
 	}
 
 	if (subscr->lac != mmctx->ra.lac)
diff --git a/openbsc/src/gprs/gtphub_ares.c b/openbsc/src/gprs/gtphub_ares.c
index 947f2dd..667013b 100644
--- a/openbsc/src/gprs/gtphub_ares.c
+++ b/openbsc/src/gprs/gtphub_ares.c
@@ -55,7 +55,7 @@
 
 	struct gtphub *hub;
 
-	char imsi_str[GSM_IMSI_LENGTH];
+	char imsi_str[GSM23003_IMSI_MAX_DIGITS+1];
 	char apn_ni_str[GSM_APN_LENGTH];
 	char apn_oi_str[GSM_APN_LENGTH];
 	int have_3dig_mnc;