Security update for samba (moderate)

Samba was updated to 4.6.15, bringing bug and security fixes. (bsc#1110943)

Following security issues were fixed:

• CVE-2018-10919: Fix unauthorized attribute access via searches.
  (bsc#1095057);

Non-security bugs fixed:

• Fix ctdb_mutex_ceph_rados_helper deadlock (bsc#1102230).
• Allow idmap_rid to have primary group other than "Domain Users"
  (bsc#1087931).
• winbind: avoid using fstrcpy in _dual_init_connection.
• Fix ntlm authentications with "winbind use default domain = yes"
  (bsc#1068059).

This update was imported from the SUSE:SLE-12-SP3:Update update project.