[tracker] docs/tools: Initialise g_autofree variables before use

[Sam Thursfield <sthursfield src gnome org>]

commit c1d0e107168832300b6b11a7c05d2bea4412600c
Author: Sam Thursfield <sam afuera me uk>
Date:   Mon Jul 6 12:13:24 2020 +0200

    docs/tools: Initialise g_autofree variables before use

 docs/tools/ttlresource2xml.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/docs/tools/ttlresource2xml.c b/docs/tools/ttlresource2xml.c
index c21b3fc2c..953366938 100644
--- a/docs/tools/ttlresource2xml.c
+++ b/docs/tools/ttlresource2xml.c
@@ -600,7 +600,7 @@ print_ontology_class (Ontology      *ontology,
                       OntologyClass *klass,
                       FILE          *f)
 {
-       g_autofree gchar *name, *id;
+       g_autofree gchar *name = NULL, *id = NULL;
 
        g_return_if_fail (f != NULL);