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/expand_test.go

@@ -163,6 +163,7 @@ var expandTestCases = []struct {
 }
 
 func TestExpand(t *testing.T) {
+	t.Parallel()
 	for _, test := range expandTestCases {
 		got, err := Expand(test.in, func(s string) (string, error) {
 			s, _, err := expander(s)
@@ -179,6 +180,7 @@ func TestExpand(t *testing.T) {
 }
 
 func TestExpandNinjaEscaped(t *testing.T) {
+	t.Parallel()
 	for _, test := range expandTestCases {
 		got, err := ExpandNinjaEscaped(test.in, expander)
 		if err != nil && !test.err {