Update to Samba 3.6.4

This is a security release in order to address
CVE-2012-1182 ("root" credential remote code execution).

o  CVE-2012-1182:
  Samba 3.0.x to 3.6.3 are affected by a
  vulnerability that allows remote code
  execution as the "root" user.

Changes since 3.6.3:
--------------------

o  Stefan Metzmacher <metze@samba.org>
    *BUG 8815: PIDL based autogenerated code allows overwriting beyond of
    allocated array (CVE-2012-1182).

(asau)