Do not use g_autofree

The g_auto macros are available only with GCC-compatible compilers on
Unix, but having __attribute__((cleanup)) is not part of our toolchain
requirements, so we shouldn't use it — even if we are building on
Unix-compatible systems.

https://bugzilla.gnome.org/show_bug.cgi?id=794732

gio/gdocumentportal.c

@@ -203,7 +203,7 @@ g_document_portal_add_documents (GList       *uris,
     {
       const char *uri = l->data;
       int idx = -1;
-      g_autofree char *path = NULL;
+      char *path = NULL;
 
       path = g_filename_from_uri (uri, NULL, NULL);
       if (path != NULL)
@@ -221,6 +221,8 @@ g_document_portal_add_documents (GList       *uris,
             }
         }
 
+      g_free (path);
+
       if (idx != -1)
         g_variant_builder_add (&builder, "h", idx);
       else