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/cc/sdk_test.go b/cc/sdk_test.go
index 5a3c181..7b9867c 100644
--- a/cc/sdk_test.go
+++ b/cc/sdk_test.go
@@ -21,6 +21,7 @@
 )
 
 func TestSdkMutator(t *testing.T) {
+	t.Parallel()
 	bp := `
 		cc_library {
 			name: "libsdk",