Write Data Saver setting to BPF map

The information is needed by modules who want to know whether a
specific UID is blocked by Data Saver feature.

1. Add a one-element map data_saver_enabled_map.
2. Update current data saver setting to the map.

Bug: 288340533
Test: atest FrameworksNetTests:android.net.connectivity.com.android.serv
er.BpfNetMapsTest
Test: atest bpf_existence_test

Change-Id: I981da4b569247c33cba2d365cb6f2691f673474e
diff --git a/bpf_progs/netd.h b/bpf_progs/netd.h
index 2b28f06..f960dcf 100644
--- a/bpf_progs/netd.h
+++ b/bpf_progs/netd.h
@@ -126,6 +126,7 @@
 static const int UID_OWNER_MAP_SIZE = 4000;
 static const int INGRESS_DISCARD_MAP_SIZE = 100;
 static const int PACKET_TRACE_BUF_SIZE = 32 * 1024;
+static const int DATA_SAVER_ENABLED_MAP_SIZE = 1;
 
 #ifdef __cplusplus
 
@@ -172,6 +173,7 @@
 #define INGRESS_DISCARD_MAP_PATH BPF_NETD_PATH "map_netd_ingress_discard_map"
 #define PACKET_TRACE_RINGBUF_PATH BPF_NETD_PATH "map_netd_packet_trace_ringbuf"
 #define PACKET_TRACE_ENABLED_MAP_PATH BPF_NETD_PATH "map_netd_packet_trace_enabled_map"
+#define DATA_SAVER_ENABLED_MAP_PATH BPF_NETD_PATH "map_netd_data_saver_enabled_map"
 
 #endif // __cplusplus