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

android/depset_test.go

@@ -64,6 +64,7 @@ func ExampleDepSet_ToSortedList() {
 // Tests based on Bazel's ExpanderTestBase.java to ensure compatibility
 // https://github.com/bazelbuild/bazel/blob/master/src/test/java/com/google/devtools/build/lib/collect/nestedset/ExpanderTestBase.java
 func TestDepSet(t *testing.T) {
+	t.Parallel()
 	a := PathForTesting("a")
 	b := PathForTesting("b")
 	c := PathForTesting("c")
@@ -274,6 +275,7 @@ func TestDepSet(t *testing.T) {
 }
 
 func TestDepSetInvalidOrder(t *testing.T) {
+	t.Parallel()
 	orders := []DepSetOrder{POSTORDER, PREORDER, TOPOLOGICAL}
 
 	run := func(t *testing.T, order1, order2 DepSetOrder) {