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/rust/test_test.go b/rust/test_test.go
index fea2ad0..bb4695a 100644
--- a/rust/test_test.go
+++ b/rust/test_test.go
@@ -22,6 +22,7 @@
 )
 
 func TestRustTest(t *testing.T) {
+	t.Parallel()
 	ctx := testRust(t, `
 		rust_test_host {
 			name: "my_test",
@@ -37,6 +38,7 @@
 }
 
 func TestRustTestLinkage(t *testing.T) {
+	t.Parallel()
 	ctx := testRust(t, `
 		rust_test {
 			name: "my_test",