v.external: fix format not a string literal and no format arguments compilation issue

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@69159 15284696-431f-4ddb-bdfa-cd5b030d7da7

vector/v.external/main.c

@@ -219,7 +219,7 @@ int main(int argc, char *argv[])
 	    strcat(error_msg,
 		   _("Consider generating a new location with 'location' parameter"
 		    " from input data set.\n"));
-            G_fatal_error(error_msg);
+            G_fatal_error("%s", error_msg);
 	}
 	else {
             G_verbose_message(_("Projection of input dataset and current location "