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/zip/zip_test.go b/zip/zip_test.go
index 302a749..9e1ef90 100644
--- a/zip/zip_test.go
+++ b/zip/zip_test.go
@@ -102,6 +102,7 @@
 }
 
 func TestZip(t *testing.T) {
+	t.Parallel()
 	testCases := []struct {
 		name               string
 		args               *FileArgsBuilder
@@ -530,6 +531,7 @@
 }
 
 func TestReadRespFile(t *testing.T) {
+	t.Parallel()
 	testCases := []struct {
 		name, in string
 		out      []string
@@ -602,6 +604,7 @@
 }
 
 func TestSrcJar(t *testing.T) {
+	t.Parallel()
 	mockFs := pathtools.MockFs(map[string][]byte{
 		"wrong_package.java":       []byte("package foo;"),
 		"foo/correct_package.java": []byte("package foo;"),