v.info: Add vector name to no db connection message (#2434)

The error message about missing database connection for a given layer does not include vector name which may not be clear when scripting or when getting the errors from underlying calls to v.info.

vector/v.info/print.c

@@ -147,8 +147,9 @@ void print_columns(const struct Map_info *Map, const char *input_opt,
               field_opt);
 
     if ((fi = Vect_get_field2(Map, field_opt)) == NULL)
-        G_fatal_error(_("Database connection not defined for layer <%s>"),
-                      field_opt);
+        G_fatal_error(
+            _("Database connection not defined for layer <%s> of <%s>"),
+            field_opt, input_opt);
     driver = db_start_driver(fi->driver);
     if (driver == NULL)
         G_fatal_error(_("Unable to open driver <%s>"), fi->driver);