r6149: Fixes bugs #2498 and 2484.

r6149: Fixes bugs #2498 and 2484.

1. using smbc_getxattr() et al, one may now request all access control
   entities in the ACL without getting all other NT attributes.
2. added the ability to exclude specified attributes from the result set
   provided by smbc_getxattr() et al, when requesting all attributes,
   all NT attributes, or all DOS attributes.
3. eliminated all compiler warnings, including when --enable-developer
   compiler flags are in use.  removed -Wcast-qual flag from list, as that
   is specifically to force warnings in the case of casting away qualifiers.

Note: In the process of eliminating compiler warnings, a few nasties were
      discovered.  In the file libads/sasl.c, PRIVATE kerberos interfaces
      are being used; and in libsmb/clikrb5.c, both PRIAVE and DEPRECATED
      kerberos interfaces are being used.  Someone who knows kerberos
      should look at these and determine if there is an alternate method
      of accomplishing the task.