Add SKIP_IF_BPF_NOT_SUPPORTED macro in BpfNetworkStatsHelperTest.

Notice that BpfNetworkStatsHelperTest testcase fails in some platforms
who doesn't support BPF feature.

Test: BpfBasicTest netd_unit_test netd_integration_test
Change-Id: I36737c567782db1c3b6561a0b6b259dec4eca945
diff --git a/libnetdbpf/BpfNetworkStatsTest.cpp b/libnetdbpf/BpfNetworkStatsTest.cpp
index a64fca9..aa73144 100644
--- a/libnetdbpf/BpfNetworkStatsTest.cpp
+++ b/libnetdbpf/BpfNetworkStatsTest.cpp
@@ -538,6 +538,8 @@
 // Test to verify that subtract overflow will not be triggered by the compare function invoked from
 // sorting. See http:/b/119193941.
 TEST_F(BpfNetworkStatsHelperTest, TestGetStatsSortAndOverflow) {
+    SKIP_IF_BPF_NOT_SUPPORTED;
+
     updateIfaceMap(IFACE_NAME1, IFACE_INDEX1);
 
     StatsValue value1 = {