SOLARIS: Perform daemon syscalls as kernel threads

SOLARIS: Perform daemon syscalls as kernel threads

Add AFS_SUN5_ENV to the list of platforms where AFS_DAEMONOP_ENV is
defined. Implement the necessary functionality so we spawn kernel
threads when a daemon syscall is called. Remove the rxk_Listener
wrapper, since it will be called in a separate thread via the
afs_DaemonOp interface.

Change-Id: I3c2570696a83f1837d08522fdd9dfc30dfefda4b
Reviewed-on: http://gerrit.openafs.org/4189
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>