[seahorse] Fix segfault when built with ldap disabled

[Niels De Graef <nielsdg src gnome org>]

commit 6fc0e3e321cdf0bf7e047234561fe8a8084a93f9
Author: Xi Ruoyao <xry111 mengyan1223 wang>
Date:   Wed Apr 14 23:18:06 2021 +0800

    Fix segfault when built with ldap disabled
    
    Fixes #321.

 pgp/seahorse-pgp-backend.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/pgp/seahorse-pgp-backend.c b/pgp/seahorse-pgp-backend.c
index 25febf31..8c10e7e3 100644
--- a/pgp/seahorse-pgp-backend.c
+++ b/pgp/seahorse-pgp-backend.c
@@ -445,7 +445,10 @@ seahorse_pgp_backend_add_remote (SeahorsePgpBackend   *self,
         /* Don't persist, so just immediately create a ServerSource */
         g_autoptr(SeahorseServerSource) ssrc = NULL;
         ssrc = seahorse_server_category_create_server (uri);
-        g_list_store_append (G_LIST_STORE (self->remotes), ssrc);
+        /* If the scheme of the uri is ldap, but ldap support is disabled
+         * in the build, ssrc will be NULL. */
+        if (ssrc)
+            g_list_store_append (G_LIST_STORE (self->remotes), ssrc);
     }
 }