Skip BpfExistenceTest#TestPrograms on BPF unsupported device

BPF is supported after kernel 4.9. Skip the test on BPF
unsupported device. Ex: walleye.

Bug: 219696135
Test: atest bpf_existence_test on walleye
Change-Id: I583a858587c0501582c9e77c8b584b3136312cd5
diff --git a/tests/mts/Android.bp b/tests/mts/Android.bp
index 2c44010..74fee3d 100644
--- a/tests/mts/Android.bp
+++ b/tests/mts/Android.bp
@@ -27,6 +27,9 @@
         "connectivity-mainline-presubmit-cc-defaults",
     ],
     require_root: true,
+    header_libs: [
+        "bpf_headers",
+    ],
     static_libs: [
         "libbase",
         "libmodules-utils-build",