Allow clatd to use local/unix datagram socket inherited from netd.

Addresses denials such as:
avc:  denied  { read write } for  pid=3142 comm="clatd" path="socket:[12029]" dev="sockfs" ino=12029 scontext=u:r:clatd:s0 tcontext=u:r:netd:s0 tclass=unix_dgram_socket

Change-Id: I5111410870c71bbfaf6b5310d8f5fd8f10db4f20
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>