better constraint failure reporting

diff --git a/skeletons/GeneralizedTime.c b/skeletons/GeneralizedTime.c
index 25f2bb6..1da113b 100644
--- a/skeletons/GeneralizedTime.c
+++ b/skeletons/GeneralizedTime.c
@@ -107,8 +107,8 @@
 	tloc = asn_GT2time(st, 0, 0);
 	if(tloc == -1 && errno != EPERM) {
 		_ASN_ERRLOG(app_errlog, app_key,
-			"%s: Invalid time format: %s",
-			td->name, strerror(errno));
+			"%s: Invalid time format: %s (%s:%d)",
+			td->name, strerror(errno), __FILE__, __LINE__);
 		return -1;
 	}