sepolicy: grant network_stack CAP_WAKE_ALARM

It is effectively an oversight that bluetooth has this
but network stack does not.

This prevents the network stack process from (for example)
using timerfd_create with CLOCK_{REAL,BOOT}TIME_ALARM,
without trampolining through parts of the mainline module
which are shipped as part of the system server.

See:
  https://man7.org/linux/man-pages/man2/timerfd_create.2.html

Bug: 316171727
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Iba95c80f830784a587fa4df6867a99bcb96ace79
diff --git a/private/network_stack.te b/private/network_stack.te
index 8e09be8..7587c1f 100644
--- a/private/network_stack.te
+++ b/private/network_stack.te
@@ -13,6 +13,8 @@
     net_raw
 };
 
+allow network_stack self:global_capability2_class_set wake_alarm;
+
 # Allow access to net_admin ioctl, DHCP server uses SIOCSARP
 allowxperm network_stack self:udp_socket ioctl priv_sock_ioctls;