sysdb: Search also aliases in sysdb_search_object_by_name
    
    sysdb_search_object_by_name did not work well case insensitive domain.
    
    Resolves:
    https://fedorahosted.org/sssd/ticket/3284
    
    Reviewed-by: Pavel Březina <pbrezina@redhat.com>
    (cherry picked from commit 8a4a2b87f51462ac22bf6db93927484841f098c6)
    (cherry picked from commit 64ef6ab9a432d6fdd231d5f96887ecabeb2fc39e)