Add XFAIL kern tests for mmap, xattrs

In prep for upstream work on mmap and xattrs.

t46	Set/get trusted.* extended attributes
t47	Set/get security.* extended attributes
t48	Run fsx with mmap read test enabled
t49	Run fsx with mmap write test enabled
add kern/t46, kern/t47 to expected PASS tests

This reflects new xattr code posted to v9fs-developer and incorporated
into 9p-sac in 2.6.38.5-23.
revert auth_required_ctl configuration

This was really the wrong way to go about this.
ctl should be able to be exported like any other path.
Require that "ctl" be explicitly exported.

This allows export options such as "ro" and "noauth" to be applied
to the ctl file system.

As part of the restructuring needed to implement this, the handling
of "ro" was moved to libnpfs so that it applies to both "ctl" and
the Npsrv abstract file system, in this case diod.

N.B. Tools that use ctl (like dtop) will no longer function until
"ctl" is added to the export list in diod.conf.
prep for 1.0.21 tag