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

java/jacoco_test.go

@@ -17,6 +17,7 @@ package java
 import "testing"
 
 func TestJacocoFilterToSpecs(t *testing.T) {
+	t.Parallel()
 	testCases := []struct {
 		name, in, out string
 	}{
@@ -66,6 +67,7 @@ func TestJacocoFilterToSpecs(t *testing.T) {
 }
 
 func TestJacocoFiltersToZipCommand(t *testing.T) {
+	t.Parallel()
 	testCases := []struct {
 		name               string
 		includes, excludes []string