Make lots of tests run in parallel

Putting t.Parallel() in each test makes them run in parallel.
Additional t.Parallel() could be added to each subtest, although
that requires making a local copy of the loop variable for
table driven tests.

Test: m checkbuild
Change-Id: I5d9869ead441093f4d7c5757f2447385333a95a4

bpf/bpf_test.go

@@ -66,6 +66,7 @@ func testContext(config android.Config) *android.TestContext {
 }
 
 func TestBpfDataDependency(t *testing.T) {
+	t.Parallel()
 	bp := `
 		bpf {
 			name: "bpf.o",