Allow binder services to use pipes passed over binder.

Resolves denials such as:
avc:  denied  { write } for  pid=18959 comm="dumpsys" path="pipe:[42013]" dev="pipefs" ino=42013 scontext=u:r:surfaceflinger:s0 tcontext=u:r:untrusted_app:s0 tclass=fifo_file
avc:  denied  { use } for  pid=18959 comm="dumpsys" path="pipe:[42013]" dev="pipefs" ino=42013 scontext=u:r:keystore:s0 tcontext=u:r:untrusted_app:s0 tclass=fd
avc:  denied  { use } for  pid=18959 comm="dumpsys" path="pipe:[42013]" dev="pipefs" ino=42013 scontext=u:r:healthd:s0 tcontext=u:r:untrusted_app:s0 tclass=fd
avc:  denied  { write } for  pid=18959 comm="dumpsys" path="pipe:[42013]" dev="pipefs" ino=42013 scontext=u:r:drmserver:s0 tcontext=u:r:untrusted_app:s0 tclass=fifo_file
avc:  denied  { use } for  pid=18959 comm="dumpsys" path="pipe:[42013]" dev="pipefs" ino=42013 scontext=u:r:inputflinger:s0 tcontext=u:r:untrusted_app:s0 tclass=fd
avc:  denied  { write } for  pid=18959 comm="dumpsys" path="pipe:[42013]" dev="pipefs" ino=42013 scontext=u:r:inputflinger:s0 tcontext=u:r:untrusted_app:s0 tclass=fifo_file
avc:  denied  { write } for  pid=18959 comm="dumpsys" path="pipe:[42013]" dev="pipefs" ino=42013 scontext=u:r:mediaserver:s0 tcontext=u:r:untrusted_app:s0 tclass=fifo_file

Change-Id: I289dcf4b2c5897b7a10e41e5dd8d56ef4b9a4a08
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>