cosmetic: use osmo_strlcpy() everywhere

Shorten some code and make obvious to the reader that the string copy is done
in a safe way.

Change-Id: I900726cf06d34128db22a3d3d911ee0d1423b1bd
diff --git a/openbsc/src/libcommon/gsm_subscriber_base.c b/openbsc/src/libcommon/gsm_subscriber_base.c
index 1f98cc6..1ecdee5 100644
--- a/openbsc/src/libcommon/gsm_subscriber_base.c
+++ b/openbsc/src/libcommon/gsm_subscriber_base.c
@@ -28,6 +28,7 @@
 #include <assert.h>
 
 #include <osmocom/core/talloc.h>
+#include <osmocom/core/utils.h>
 #include <openbsc/gsm_subscriber.h>
 #include <openbsc/debug.h>
 
@@ -115,7 +116,7 @@
 	if (!subscr)
 		return NULL;
 
-	strncpy(subscr->imsi, imsi, sizeof(subscr->imsi)-1);
+	osmo_strlcpy(subscr->imsi, imsi, sizeof(subscr->imsi));
 	subscr->group = sgrp;
 	return subscr;
 }