zygote requires setpcap in order to drop from its bounding set.

I8560fa5ad125bf31f0d13be513431697bc7d22bb changed the zygote
to limit the bounding capability set to CAP_NET_RAW.  This triggers
a CAP_SETPCAP check by the kernel, which requires SELinux setpcap permission.

Change-Id: Ib910d97dcf708273e2806e2824f4abe9fc239d6d
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>