[vala/0.40] libvaladoc/girimporter: Fallback to "name" for callback

[Rico Tzschichholz <ricotz src gnome org>]

commit 9e2629717c9b8b92a43ad0f76c0378bb80e0d5bd
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Thu Aug 27 10:02:19 2020 +0200

    libvaladoc/girimporter: Fallback to "name" for callback
    
    This caused criticals like:
    
      valadoc_importer_gir_documentation_importer_attach_comment: assertion 'cname != NULL' failed

 libvaladoc/importer/girdocumentationimporter.vala | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/libvaladoc/importer/girdocumentationimporter.vala 
b/libvaladoc/importer/girdocumentationimporter.vala
index 1ce11b39c..b03e2971c 100644
--- a/libvaladoc/importer/girdocumentationimporter.vala
+++ b/libvaladoc/importer/girdocumentationimporter.vala
@@ -655,6 +655,9 @@ public class Valadoc.Importer.GirDocumentationImporter : DocumentationImporter {
 
                case "callback":
                        c_identifier = reader.get_attribute ("c:type");
+                       if (c_identifier == null) {
+                               c_identifier = reader.get_attribute ("name");
+                       }
                        break;
 
                case "virtual-method":