Migrate bpf package to a per test build directory

Bug: 182885307
Test: m nothing
Change-Id: I0ee9575af056057ca37831a3afebba2be1e54d27

bpf/bpf_test.go

@@ -15,7 +15,6 @@
 package bpf
 
 import (
-	"io/ioutil"
 	"os"
 	"testing"
 
@@ -23,34 +22,12 @@ import (
 	"android/soong/cc"
 )
 
-var buildDir string
-
-func setUp() {
-	var err error
-	buildDir, err = ioutil.TempDir("", "genrule_test")
-	if err != nil {
-		panic(err)
-	}
-}
-
-func tearDown() {
-	os.RemoveAll(buildDir)
-}
-
 func TestMain(m *testing.M) {
-	run := func() int {
-		setUp()
-		defer tearDown()
-
-		return m.Run()
-	}
-
-	os.Exit(run())
-
+	os.Exit(m.Run())
 }
 
 var bpfFactory = android.NewFixtureFactory(
-	&buildDir,
+	nil,
 	cc.PrepareForTestWithCcDefaultModules,
 	android.FixtureMergeMockFs(
 		map[string][]byte{