enable btf = true for block/clatd/dscp_policy/netd bpf programs

(we avoid offload - for now - due to that being shipped to <T devices)

Before:
  $ adbz shell ls -l /apex/com.android.tethering/etc/bpf/net_shared/*.o
  -rw-r--r-- 1 system system  2848 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/net_shared/block.o
  -rw-r--r-- 1 system system 10240 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/net_shared/clatd.o
  -rw-r--r-- 1 system system 16144 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/net_shared/dscp_policy.o
  -rw-r--r-- 1 system system 18840 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/net_shared/netd.o

After:
  $ adbz shell ls -l /apex/com.android.tethering/etc/bpf/net_shared/*.o
  -rw-r--r-- 1 system system  6192 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/net_shared/block.o
  -rw-r--r-- 1 system system 19008 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/net_shared/clatd.o
  -rw-r--r-- 1 system system 23960 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/net_shared/dscp_policy.o
  -rw-r--r-- 1 system system 27112 1969-12-31 16:00 /apex/com.android.tethering/etc/bpf/net_shared/netd.o

So there is a minor increase in .o size, but this allows:

$ adbz shell cat /sys/fs/bpf/net_shared/map_netd_iface_index_name_map
  # WARNING!! The output is for debug purpose only
  # WARNING!! The output format will change
  8: {['e','r','s','p','a','n','0',],}
  1: {['l','o',],}
  4: {['i','f','b','1',],}
  2: {['d','u','m','m','y','0',],}
  16: {['e','t','h','1',],}
  5: {['t','u','n','l','0',],}
  14: {['h','w','s','i','m','0',],}
  17: {['w','l','a','n','0',],}
  12: {['i','p','6','t','n','l','0',],}
  18: {['w','l','a','n','1',],}
  13: {['i','p','6','g','r','e','0',],}
  3: {['i','f','b','0',],}
  15: {['b','u','r','i','e','d','_','e','t','h','0',],}
  9: {['i','p','_','v','t','i','0',],}
  11: {['s','i','t','0',],}
  10: {['i','p','6','_','v','t','i','0',],}
  6: {['g','r','e','0',],}
  7: {['g','r','e','t','a','p','0',],}

This is safe as the net_shared bpf programs are not loaded on pre-T devices,
and the T bpfloader is btf enabled.

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I2d480391b6d1a6e2ba99b0445281684d4a51d74b
diff --git a/bpf_progs/Android.bp b/bpf_progs/Android.bp
index 0e7b22d..6c78244 100644
--- a/bpf_progs/Android.bp
+++ b/bpf_progs/Android.bp
@@ -61,6 +61,7 @@
 bpf {
     name: "block.o",
     srcs: ["block.c"],
+    btf: true,
     cflags: [
         "-Wall",
         "-Werror",
@@ -71,6 +72,7 @@
 bpf {
     name: "dscp_policy.o",
     srcs: ["dscp_policy.c"],
+    btf: true,
     cflags: [
         "-Wall",
         "-Werror",
@@ -99,6 +101,7 @@
 bpf {
     name: "clatd.o",
     srcs: ["clatd.c"],
+    btf: true,
     cflags: [
         "-Wall",
         "-Werror",
@@ -112,6 +115,7 @@
 bpf {
     name: "netd.o",
     srcs: ["netd.c"],
+    btf: true,
     cflags: [
         "-Wall",
         "-Werror",