zygote: grant perms from domain_deprecated

In preparation of removing permissions from domain_deprecated.

Addresses:
avc: denied { read } for name="ipv6_route" dev="proc" ino=4026536875 scontext=u:r:zygote:s0 tcontext=u:object_r:proc_net:s0 tclass=file
avc: denied { open } for path="/proc/220/net/ipv6_route" dev="proc" ino=4026536875 scontext=u:r:zygote:s0 tcontext=u:object_r:proc_net:s0 tclass=file
avc: denied { getattr } for path="/proc/220/net/ipv6_route" dev="proc" ino=4026536875 scontext=u:r:zygote:s0 tcontext=u:object_r:proc_net:s0 tclass=file

Change-Id: Ie94d3db3c5dccb8077ef5da26221a6413f5d19c2