Create proc_net type for /proc/sys/net entries.

/proc/sys/net could use its own type to help distinguish
among some of the proc access rules. Fix dhcp and netd
because of this.

Change-Id: I6e16cba660f07bc25f437bf43e1eba851a88d538
Signed-off-by: rpcraig <rpcraig@tycho.ncsc.mil>
diff --git a/genfs_contexts b/genfs_contexts
index 8560e38..99d4400 100644
--- a/genfs_contexts
+++ b/genfs_contexts
@@ -15,6 +15,7 @@
 genfscon proc /sys/kernel/poweroff_cmd u:object_r:usermodehelper:s0
 genfscon proc /sys/kernel/randomize_va_space u:object_r:proc_security:s0
 genfscon proc /sys/kernel/usermodehelper u:object_r:usermodehelper:s0
+genfscon proc /sys/net u:object_r:proc_net:s0
 genfscon proc /sys/vm/mmap_min_addr u:object_r:proc_security:s0
 # selinuxfs booleans can be individually labeled.
 genfscon selinuxfs / u:object_r:selinuxfs:s0