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
diff --git a/java/hiddenapi_singleton_test.go b/java/hiddenapi_singleton_test.go
index dbdab7a..97dd125 100644
--- a/java/hiddenapi_singleton_test.go
+++ b/java/hiddenapi_singleton_test.go
@@ -58,6 +58,7 @@
 }
 
 func TestHiddenAPISingleton(t *testing.T) {
+	t.Parallel()
 	ctx, _ := testHiddenAPIBootJars(t, `
 		java_library {
 			name: "foo",
@@ -75,6 +76,7 @@
 }
 
 func TestHiddenAPISingletonWithPrebuilt(t *testing.T) {
+	t.Parallel()
 	ctx, _ := testHiddenAPIBootJars(t, `
 		java_import {
 			name: "foo",
@@ -92,6 +94,7 @@
 }
 
 func TestHiddenAPISingletonWithPrebuiltUseSource(t *testing.T) {
+	t.Parallel()
 	ctx, _ := testHiddenAPIBootJars(t, `
 		java_library {
 			name: "foo",
@@ -121,6 +124,7 @@
 }
 
 func TestHiddenAPISingletonWithPrebuiltOverrideSource(t *testing.T) {
+	t.Parallel()
 	ctx, _ := testHiddenAPIBootJars(t, `
 		java_library {
 			name: "foo",
@@ -150,6 +154,7 @@
 }
 
 func TestHiddenAPISingletonSdks(t *testing.T) {
+	t.Parallel()
 	testCases := []struct {
 		name             string
 		unbundledBuild   bool