Do not attempt to read use-gss-proxy file in procfs

The networking plug-in scoops up /proc/net. There are some pseudo-
files in here that we should avoid touching. These either have
side-effects or hang the reading process.

Add a forbidden path for the /proc/net/rpc/use-gss-proxy file.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Do not attempt to read use-gss-proxy file in procfs

The networking plug-in scoops up /proc/net. There are some pseudo-
files in here that we should avoid touching. These either have
side-effects or hang the reading process.

Add a forbidden path for the /proc/net/rpc/*/{channel,flush}
files as these will cause side-effects for RPC applications
running on the host.

Forward port of commit 61585d4 on rhel-6 branch.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>